G684 Basalt (Fuding Black)

What Is G684 Basalt?

G684 is a fine-grained black basalt quarried at Fuding in Fujian Province, China, sold internationally as Fuding Black, Black Pearl, Panda Black, Twilight and Palladio Dark. Despite the "G" prefix — which in the Chinese stone trade signals granite — it is a volcanic rock, not a granite, and is occasionally classified more precisely as an olivine basalt or tephrite. It is one of the few inexpensive black stones that does not turn grey after flame treatment, which is the single biggest reason it became a standard specification for exterior paving and pool surrounds.

That naming history matters commercially. Because "black granite" is not a protected term and the G-code is the only reliable identifier, buyers occasionally receive G684 when they believed they were buying Shanxi Black or another higher-priced black. The two stones differ in density, porosity and how they age. If your specification calls for a specific black, name the code, not the colour.

Where it comes from

The quarry district sits around Fuding and the wider Ningde–Fujian volcanic belt. Material is cut at factories clustered near Shuitou and Xiamen, and the overwhelming majority exports through Xiamen port. That concentration is useful for buyers: a single province holds the quarry, the processing capacity and the shipping infrastructure, which keeps lead times short relative to stones that must be trucked across provinces before fabrication.

G684 Technical Specifications

Published test data for G684 varies somewhat between suppliers, which is normal for natural stone — different quarry benches and different laboratories produce different numbers. The ranges below are drawn from multiple published sources; treat them as indicative and request the test report for your actual lot.

What the numbers mean on site

Water absorption is the number that matters most for exterior work. At 0.07–0.18%, G684 absorbs roughly half the moisture of G654. In a freeze-thaw climate, absorbed water is what cracks stone: it enters the pore structure, freezes, expands, and repeats. Lower absorption does not make a stone immune to frost damage, but it moves the risk downward — and it is why G684 appears on so many northern European and North American pool decks and driveways.

Compressive strength figures should be read with caution. The published range for G684 is unusually wide, from around 110 MPa to 289 MPa. Almost every one of those values is far above what a paving or cladding application will ever impose. If you are buying paving, the number is not your constraint — dimensional tolerance, surface finish consistency and packing are. If you are engineering a structural element, insist on a project-specific test report rather than a brochure figure.

Density drives your freight cost. At roughly 2.9–3.0 g/cm³, G684 is heavier than most granites per cubic metre. A container of G684 will therefore cover slightly less area than the same container of a lighter stone at the same thickness. This is a real cost in the landed price and is worth calculating before comparing quotes between stones.

G684 vs G654 and Other Black Stones

G684 vs G654

These two are the most commonly confused Chinese dark stones, and the differences are practical rather than cosmetic.

G654 is a genuine granite from the Changtai–Zhangzhou area of Fujian, and it is dark grey, not black. Its structure is a visible salt-and-pepper grain, and it only looks convincingly dark when wet. G684 is finer-grained and closer to true black. The decisive difference appears after flame treatment: G654 tends to read grey once it has been flamed, whereas G684 holds its darkness. For a black exterior pavement, that alone usually settles the choice.

On performance, G684 is denser and less absorbent. G654 is the more economical of the two and is widely used where large areas must be covered to a budget — it is an excellent value paving stone, just not a black one.

Because G684 is the darkest of the common Chinese basalts, it is also marketed as "absolute black basalt" — a trade description rather than a geological one, and not to be confused with Absolute Black granite, which is a different stone from a different quarry.

A note on codes: some references now list G654 under the newer four-digit system as G3554. If a supplier quotes "G3554", confirm whether it is the same material you specified as G654 before comparing prices.

G684 vs Shanxi Black and Absolute Black

Shanxi Black and Absolute Black are true black granites with finer, more uniform colour and a higher price. They polish to a deeper, more consistent black and are the usual choice for premium countertops, memorials and interior feature work. G684 is the budget alternative for exterior work. Suppliers sometimes present G684 as a cheap route to "black granite", which is true up to a point — but see the sunlight note below before specifying polished G684 for a facade.

Why the "basalt vs granite" distinction is worth knowing

Basalt and granite behave differently in a few ways that matter at the specification stage. Basalt is generally more sensitive to acidic cleaning products than granite, so specify pH-neutral cleaners and make sure the maintenance contractor knows. Basalt also tends to be denser, which affects freight. On the other hand, its fine grain gives a more uniform surface than the coarse speckle of many granites, which is precisely what designers want from a black stone.

Available Products and Formats

G684 is produced across the full range of dimension-stone formats. The list below covers what we cut most often; other formats are available on request.

G684 Slabs

Gangsaw slabs are typically supplied in 2 cm and 3 cm thicknesses, with 4, 5, 6, 8, 10 and 12 cm available to order. Standard slab dimensions run up to roughly 2400–3000 mm × 1200–1900 mm depending on the block. Polished, honed and flamed finishes are all produced. Slabs are bundled for container shipment, typically up to around 12 pieces per bundle at 20 mm and 7–9 pieces at 30 mm, with several bundles per 20ft container.

Because G684 is a fine-grained stone, slab-to-slab colour variation is smaller than for most marbles — but it is not zero. For book-matched or vein-continuous work, ask for photographs of the actual bundle before cutting.

G684 Tiles and Cut-to-Size

G684 basalt stone tiles are supplied in standard sizes including 300×300, 300×600, 400×400, 600×600 and 800×800 mm, along with the imperial equivalents common in North American specifications. Thicknesses of 10, 15, 18, 20 and 30 mm are all produced. Cut-to-size work is the norm rather than the exception: most buyers send a cutting list and receive calibrated tiles to a stated tolerance.

For exterior flooring, 20 mm and above is the usual specification. For cladding, thinner material is common but should be assessed against the fixing system and wind loading of the specific project.

G684 Paving Stones and Setts

This is where G684 earns its reputation. Flamed paving in 20 mm, 30 mm and 50 mm thicknesses is used across patios, driveways, pedestrian precincts and pool surrounds. Standard paving sizes range from small setts such as 200×100 mm up to 900×600 mm. Small-format setts — 100×100, 200×100 and similar — are supplied either loose or pre-assembled on mesh backing for faster installation.

The flamed finish is the reason this works outdoors. Thermal treatment fractures the surface into a fine, slightly rough texture that provides grip when wet. A polished surface on a pool deck or a sloped driveway is a slip risk regardless of how good it looks in a photograph.

G684 Pool Coping

Pool coping is one of the strongest applications for G684 and one of the most specified. Coping caps the pool shell, forms the transition between water and deck, and takes the most concentrated wear of any stone on the site.

Typical coping sizes are 400×400×20 mm, 600×400×40/20 mm and 400×400×100/20 mm, with thicknesses of 20 mm, 40/20 mm and 50/30 mm. Edge profiles include bullnose, rebated bullnose, square edge, eased edge, drop face and matching external corners. The bullnose variants matter on a pool: a rounded edge is kinder to hands and feet and reduces chipping at the waterline.

Flamed is the standard finish for the walking surface. Some projects combine a flamed top with a polished or honed face on the vertical drop edge for a crisper waterline detail — this is a fabrication decision and is worth fixing at the drawing stage rather than after cutting.

G684 Steps and Stair Treads

G684 black basalt step treads and risers are cut to project dimensions, typically in 30 mm and 50 mm thicknesses. Customised profiles — including treads supplied customized to a client drawing, with nosing or grooved anti-slip detail — are produced to order. Standard profiles — nosing, anti-slip grooves or inserts, and rebated treads that accept a riser — are produced to drawing. Because G684 is dense and fine-grained, it takes a clean arris and holds a crisp edge well.

For exterior stairs, specify a flamed or bush-hammered top surface. For interior stairs where slip resistance is less critical, honed is the usual choice: it retains the depth of black while avoiding the mirror finish that shows every footprint.

G684 Kerbstones, Palisades and Edging

Kerbstones, palisades and edging elements are cut in a wide range of sections. Straight kerbs, radius kerbs, transitions and corner units can all be produced; palisades are commonly supplied in square or tapered sections for landscape edging and retaining work. These are typically flamed, sawn or natural-split finish, and are often supplied in container quantities alone rather than as part of a mixed load.

G684 Monuments and Memorials

G684's uniform black makes it a workable memorial stone. It takes laser etching and hand carving, and the contrast between polished black and the light-grey engraved line is strong. It sits below Shanxi Black and Absolute Black on the price ladder, which makes it a common specification for cemetery projects let to a budget. Where a memorial is exposed to decades of weather without maintenance, be aware of the sunlight and acidity notes below.

Surface Finishes

Finish selection does more to determine how G684 performs and how it looks than any other single decision.

Flamed (Thermal)

The default exterior finish. The surface is passed under a high-temperature flame, which causes the crystals at the surface to expand unevenly and flake away, leaving a textured, matt surface. Flamed G684 reads as a dark grey-black rather than a true black, because the texture scatters light. It provides grip, resists frost damage by keeping the surface open, and hides dust and footprints better than polished. For paving, driveways, pool decks and exterior steps, this is usually the right answer.

Polished

The deepest black. Polished G684 has a mirror surface and the most uniform appearance of any finish, and it is the finish that distinguishes G684 most clearly from G654. It suits interior flooring, wall cladding, countertops and feature work. It is not slip-resistant when wet, and — see below — it can lose colour depth under prolonged direct sunlight.

Honed

A smooth matt finish that keeps most of the depth of colour without the mirror. Honed G684 is a good compromise for interior floors and stairs, and for exterior applications where a polished surface would be too reflective or too slippery but a flamed texture would be visually too rough. Slip resistance depends heavily on the specific surface and must be tested for the project.

Natural Split

Split along the natural grain, producing a rough, riven surface with visible layered texture. Used for walling, feature cladding and landscape elements where a more rustic appearance is wanted. Grip is high; dimensional tolerance is naturally looser than for sawn material.

Bush-Hammered and Sandblasted

Bush-hammering gives a pronounced, evenly pitted texture with excellent grip — often used on ramps, steps and heavy-traffic paved areas where appearance is secondary to safety. Sandblasting produces a finer, more even matt surface; it is a common choice for coping and walling where a softer look is wanted.

Tumbled and Antique

Tumbling softens edges and corners and lightens the surface in places, producing a weathered appearance. It is used mainly for small-format paving and setts in period-style or landscape schemes. Note that tumbling increases the exposed surface area and can raise effective water absorption slightly on some stone types; for G684 the low base absorption leaves reasonable headroom, but the finish should still be assessed for a freeze-thaw site.

Applications

G684 is specified across both interior and exterior work. The most common applications are:

• Exterior paving and patios — flamed paving at 20–30 mm for residential and commercial hardscaping.
• Driveways and parking areas — thicker material, typically 30–50 mm, often on a concrete base.
• Pool surrounds and coping — flamed surfaces with bullnose edges.
• Steps, treads and risers — interior and exterior, to drawing.
• Wall cladding and facades — where a flamed or honed finish is normally specified, for the reason given below.
• Fountains and water features — the low absorption and frost resistance suit permanently wet conditions better than most black stones.
• Kerbing, palisades and edging — landscape and highway work.
• Monuments and memorials — polished and carved work.
• Interior flooring and stairs — honed or polished.
• Countertops and vanities — polished or honed; less common than granite or quartz in this role, but specified where the client wants a uniform black.

Across all of these, the selection logic is consistent: the more exposure to weather, water, sun or foot traffic, the more the specification should push toward flamed and thicker material, and away from polished and thin.

Sizes, Thickness and Custom Fabrication

Most G684 orders are cut to size rather than bought from stock dimensions, and the practical constraints are worth knowing before you write the specification.

Thickness. 20 mm is the standard paving and cladding thickness. 30 mm is common for driveways, heavy pedestrian traffic and steps. 50 mm and above is used for specialist paving and structural work. Below 20 mm, the stone is available but becomes increasingly sensitive to bedding quality and point loading — a 10 mm tile on an uneven substrate will fail where a 20 mm one will not.

Tolerance. Calibrated (dimensionally uniform) material costs more than uncalibrated. For paving laid to a tight joint width, calibration is usually worth the premium. Ask for the stated tolerance in millimetres rather than accepting "standard" as an answer, and confirm whether it applies to thickness as well as length and width.

Edge work. Sawn, bevelled, bullnosed, chamfered and eased edges are all producible. Edge work is a significant part of the cost of finished paving and coping, and it is where specifications most often drift between the drawing and the delivered load — so it should be confirmed in writing with a drawing, not a description.

Custom profiles. Rebated copings, dropped-face pool edges, treads with integral risers and radius kerbs are all cut to drawing. Complex profiles need longer lead times and should be prototyped and approved before the production run.

Packing and Container Loading

For an importer, this section usually matters more to the landed cost than the ex-works price. G684 is a dense, heavy stone, and the number of square metres a container will carry is fixed by weight rather than by volume.

How much fits in a container

A 20ft container loaded in a Chinese port can typically take a gross weight of around 27 tonnes, though the practical limit is usually set by road and rail weight limits at the destination rather than at the port of loading. Allow at least 1,000 kg for the weight of the wooden crates themselves.

Published loading figures for stone of this density give a useful working guide:

Two consequences follow. First, a North American buyer gets materially less stone per container than a European buyer at the same thickness, because the overland weight limit binds first. Second, comparing an ex-works price per square metre between suppliers is close to meaningless until the loading plan is known — a supplier quoting a low unit price but loading 380 m² where another loads 460 m² is not cheaper.

How it is packed

Stone for export is packed in fumigated, seaworthy wooden crates or bundles, stamped for export. Crate timber is typically 1.5–1.8 cm thick in common practice, with better factories using 2 cm. For paving, a typical loading is 8–15 pieces per bundle and 7–10 bundles per 20ft container; small setts and mesh-backed paving are usually supplied in crates weighing 1–1.5 tonnes each.

Internal protection varies with the product: PVC film or foam between slabs, carton boxes for tiles, and ton bags for pebbles and small aggregates. For slabs and finished coping, ask for photographs of the packed bundles before the container is sealed — this is the cheapest possible insurance against a chipped or mis-cut load arriving.

Quality Control and Inspection

G684 is a uniformly coloured stone, which makes visual QC comparatively straightforward — but there are specific defects worth writing into the inspection standard.

Colour and pattern consistency. First-grade G684 should be consistently black with fine, evenly distributed mineral speckle. Lower grades may show white lines or cloudy patches that are visible once laid. Because photographs under artificial light flatter black stone considerably, ask for images taken outdoors in daylight, and of a full bundle rather than a single slab.

Dimensional tolerance. For calibrated paving, check length, width, thickness and squareness against the stated figures. Thickness variation is the defect that most often causes problems on site, because it shows up as lippage across a laid pavement.

Surface defects. Chips at arrises, tool marks from inadequate finishing, and inconsistent flame treatment across a batch are all visible on inspection. Flame treatment consistency is worth a specific check on flamed paving: uneven flaming produces patches of different texture that read as colour variation once installed.

Filler. Polished G684 may carry epoxy filler in micro-fissures. This is normal trade practice and does not affect structural integrity, but it should be disclosed rather than discovered.

We photograph and record bundles at packing, and third-party pre-shipment inspection can be arranged at the buyer's request.

Pricing Factors

The G684 basalt price you see quoted per square metre is a small part of the landed cost, and it sits at the economical end of black stone. The factors that move the final number most are:

• Thickness and format. Thicker material costs more per square metre and carries less area per container.
• Finish. Flamed and sawn are the least expensive; polishing and honing add processing cost, and complex edge profiles add considerably more.
• Calibration and tolerance. Tight-tolerance calibrated material costs more than uncalibrated.
• Order quantity and container fill. Ex-works pricing is usually quoted against full-container quantities. Partial loads pay a disproportionate share of fixed costs, including inland haulage and crate timber.
• Destination. The weight limit at destination determines how much fits in the container, which changes the landed cost per square metre far more than most buyers expect.
• Duty and tariff. Trade measures vary by destination and change over time. For US imports, G684 blocks are classified for tariff purposes under HTS heading 2516.12.00 (sawn building stone), and applicable rates should be confirmed with a customs broker for the specific entry rather than taken from any published list, including this one.

Because of these variables, prices are quoted per project rather than from a list. Send a cutting list with thicknesses and finishes, and the quotation will include a loading plan.

Ordering Process and Lead Times

The sequence for a typical G684 order runs as follows:

1. Specification and samples. Confirm the stone code, finish, thickness, tolerance and edge profiles. Physical samples are available; allow for sample preparation and shipping time.
2. Quotation with loading plan. A price per square metre is quoted alongside the container loading figure, so the landed cost per square metre is visible before commitment.
3. Pre-production approval. For custom profiles, a sample piece is produced and approved. For paving, a dry-lay or bundle photograph is used to confirm colour consistency.
4. Production. Typical production time runs from around two to four weeks depending on quantity and complexity. Custom profiles and large orders take longer.
5. Packing and pre-shipment inspection. Bundles are photographed; third-party inspection can be arranged.
6. Shipping. Standard export terms include FOB, CFR/CIF and EXW. Sea freight is usually arranged either by the buyer's forwarder or by ours, per the agreed trade term.
7. Documentation. Commercial invoice, packing list, bill of lading and certificate of origin are issued for the shipment; fumigation documentation accompanies the packing.

Payment terms commonly used in the trade are a deposit against production with the balance against a copy of the bill of lading, or a letter of credit at sight. Terms are confirmed per order.

An Honest Note on G684 in Direct Sunlight

Most supplier pages about G684 do not mention this, and it belongs in any specification decision.

Polished G684 can lose depth of colour — reading lighter, greyer or more washed-out — after prolonged exposure to strong direct sunlight. The effect is gradual and depends on orientation, latitude and how polished the surface is. It is the main reason some experienced specifiers avoid high-polish G684 for open plazas, large facades and anything that will face the sun for decades without maintenance.

Practical consequences:

• For paving, pool decks and driveways: not a significant concern, because these use flamed or honed finishes, and the flamed surface already reads dark grey rather than black.
• For facades and open plazas: specify flamed, honed or split-face rather than polished. If a deep polished black is essential for the design, Shanxi Black or Absolute Black are the more stable choices, at a higher price.
• For interior work, shaded courtyards and memorials: polished G684 is generally a sound choice; the exposure is limited.
• Sealing: a penetrating sealer is commonly recommended for dark stone, and many suppliers report that sealing reduces the rate of colour change outdoors. Sealing does not make the stone colour-fast, and claims to the contrary should be treated with scepticism.

We would rather tell you this at the specification stage than have you discover it on a completed facade. If your project is sun-exposed and you want polished black, we will say so and quote the alternatives.

Why Source G684 from China

The quarry, the processing capacity and the export infrastructure for G684 are all in Fujian. That concentration has three practical effects for a buyer: product is available in volume rather than in batches, cutting to specification is routine rather than a special order, and shipping through Xiamen is well established with frequent sailings to North America, Europe, the Middle East and Australia.

The trade-off is that quality varies between factories, and the G-code alone does not guarantee a grade. The controls that matter are the ones described above — stated tolerances, bundle photographs before sealing, and inspection before shipment.

Frequently Asked Questions

Is G684 a granite or a basalt?

Geologically it is a basalt — a fine-grained volcanic rock quarried at Fuding in Fujian Province, China. It is sold with a "G" code, which in the Chinese stone trade denotes granite, because it is traded through the same channel and used for the same applications. Some sources classify it more precisely as an olivine basalt or tephrite.

What is the difference between G684 and G654?

G684 is a fine-grained black basalt; G654 is a dark grey granite with a visible salt-and-pepper grain. G684 is denser and less water-absorbent, and — the difference most buyers notice — it stays dark after flame treatment, whereas G654 tends to read grey once flamed. G654 is generally the more economical of the two.

Does G684 need sealing?

Sealing is commonly recommended, particularly for exterior applications and for dark stone generally. Its principal benefit is resistance to staining and to the ingress of moisture and pollutants. It is not a substitute for correct installation, drainage and movement joints, and it does not make the stone immune to colour change under sunlight.

How much G684 fits in a 20ft container?

At 20 mm thickness, roughly 460 m² into a container loaded to about 26 tonnes, and roughly 310 m² at 30 mm. North American destinations are usually limited to around 20.5 tonnes by overland weight rules, which reduces coverage accordingly. The exact figure depends on thickness, format and destination, and is confirmed with the quotation.

Can G684 be used for a pool deck?

Yes, and it is one of its most common applications. Flamed or bush-hammered finishes provide grip when wet, and the low water absorption and frost resistance suit permanently wet and freeze-thaw conditions. Bullnose or rebated coping profiles are used at the waterline. As with any stone, the actual slip resistance of the finished assembly depends on the specific finish and installation, and should be confirmed against the project's requirements.

Why does some black stone turn grey outdoors?

Two different mechanisms are often conflated. Flamed stone reads grey because the textured surface scatters light — this is expected and not a defect. Separately, polished dark stone can gradually lose colour depth under prolonged strong sunlight. If your project is sun-exposed and you need a durable deep black, specify polished material with caution and consider a honed or flamed finish, or a different black granite.

What finishes are available for G684?

Flamed (thermal), polished, honed, natural split, bush-hammered, sandblasted, tumbled and antique. Flamed is standard for exterior paving and coping; polished and honed for interiors, cladding and feature work; split-face for walling.

What is the minimum order?

Most G684 orders are quoted against full container loads, because partial loads carry disproportionate freight and packing costs. Smaller trial quantities can be discussed, and samples are available before commitment.

Can you cut G684 to a drawing?

Yes. Cut-to-size and custom profiling are the norm rather than the exception — paving to a cutting list, coping to a pool drawing, treads and risers to stair dimensions, and radius or transition kerbs. Custom profiles are prototyped and approved before the production run.