Granite Slab and Tile Inspection in India

How granite slabs and tiles are made

Granite is India's largest stone export by far. Exports of granite simply cut or sawn (HS 6802 23), the slabs and tiles on this page, were US$757.11 million in FY2025-26, and crude granite blocks (HS 2516 11) another US$328.14 million (Department of Commerce, TradeStat, provisional). One quarry area with an official listing is Prakasam district in Andhra Pradesh, whose One District One Product is "Granite (Black Galaxy)"; the district says this black granite is found only in Chimakurthy mandal.

Blocks are sawn into slabs on gang saws or multi-wire saws, usually 2 cm or 3 cm thick for slabs and thinner for tiles. Slabs with natural fissures are dried, filled with resin on a line and often backed with fibreglass mesh before polishing. The face is then finished:

Polished: ground through finer abrasives to a mirror shine, read with a gloss meter.
Honed: smooth and matt; shows marks and colour change more than polish does.
Flamed: heated so the surface crystals burst, for a rough, slip-resistant outdoor finish.
Leathered: brushed to a soft, textured sheen.

Tiles are cut from slabs, calibrated to an even thickness on a milling line and edge-chamfered. Countertops are cut to the buyer's drawings, with sink and hob cut-outs, edge profiles and sometimes splashbacks, then packed as kitchen sets.

What we check on granite

Check	How it is checked	What fails
Thickness	Calliper at the four corners and middle of each edge of a slab; tiles measured from several cartons	Thin spots or a wedge across the slab; tiles outside the calibration tolerance
Size and squareness	Tape and steel square; both diagonals on tiles and cut-to-size pieces	Short pieces, diagonals differing beyond tolerance
Flatness	Straightedge and feeler gauge along and across the face	Bow or dip that causes lippage on a floor or a rocking worktop
Polish	Gloss meter readings at several points per slab against the agreed minimum	Low or patchy gloss, hazy areas, polishing burns
Dye and colour enhancers	Acetone wipe on an unpolished edge or the back of black and coloured granite	Colour transferring to the cloth on stone sold as natural
Resin and mesh	Face and back checked in raking light; mesh pulled at a corner	Resin pools, cloudy or sunken fills, mesh lifting, fissures open on the face
Colour and grain	Slabs or tile cartons laid out side by side against the sample and limit pieces	Pieces outside the range; two shade lots mixed in one order
Edges and corners	Every visible edge looked at; chamfers on tiles	Chips, spalls, rough or uneven chamfer

Countertops and vanity tops

Worktops are made to order, so the drawing is the standard. The inspector checks each piece against its drawing number, not just against a sample:

Cut-outs. Size and position of sink, hob and tap holes. Inside corners should be rounded rather than cut square; a square inside corner is where a crack starts. Many factories reinforce the narrow strips beside a cut-out with steel rods set in resin under the slab.
Edge profile. Eased, bevelled, bullnose or ogee profiles checked with a template along the full length, including the polished finish inside the profile.
Joins. Where an L-shaped or long run is made of two pieces, the pieces are laid together to check that colour, grain and edge line continue across the seam.
Undermount sink edges. Polished edge inside the cut-out, as it will be seen.
Set completeness. Every piece of a kitchen set, with splashbacks and upstands, marked and packed together.

Common granite slab, tile and countertop defects and how they are classed

Defect	Typical cause	Class
Dyed stone sold as natural, or a different stone substituted	Cost or supply substitution	Critical (false description)
Crack through the slab or at a cut-out corner	Natural weakness, square inside corner, handling	Major
Thickness or calibration out of tolerance	Worn saw blades, calibration skipped	Major
Cut-out in the wrong place or wrong size	Drawing misread	Major
Colour lot mixed	Slabs from several blocks combined	Major
Patchy or low gloss	Short polishing, worn abrasives	Major or minor by extent
Visible resin pools or cloudy fills	Poor resin line control	Minor; major on a feature face
Small chip on a non-visible edge	Handling	Minor

Your defect list decides the final class.

Market rules for granite

EU and GB construction products. Natural stone slabs for cladding (EN 1469), modular tiles (EN 12057) and slabs for floors and stairs (EN 12058) are covered by harmonised European standards, so the manufacturer issues a declaration of performance and the product is CE marked. The inspector checks that pack labels and documents match the product shipped. See UKCA and CE marking.
US. ASTM C615 is the material specification for granite dimension stone, setting minimum values for properties such as absorption, density and strength. It is used in contracts; results come from a lab on stone from your blocks.
Wood packaging. Crates, A-frames and pallets must meet ISPM 15.
Origin. Country of origin on packs and invoices; see country of origin labelling.

Packing, transit and your purchase order

Slabs travel standing on edge in wooden bundles or A-frames, polished faces together with a plastic or foam sheet between them. Tiles go in cartons on pallets or in wooden crates. The risks are slabs leaning and cracking when bracing is loose, crates breaking under the weight, and grit scratching polished faces. A container of granite reaches its weight limit with space to spare, so the load must be spread and blocked; see container loading supervision.

Stone name, finish and source quarry; approved sample with light and dark limit pieces.
Thickness and tolerance; calibration for tiles; flatness limit.
Minimum gloss reading and how it is measured.
Whether resin, mesh or colour enhancers are allowed.
For worktops: drawings by piece number, edge profiles, cut-out radius and rodding.
Packing: bundle or crate type, interleaving, ISPM 15, maximum crate weight.

Book an inspection anywhere in India.

Sources

Frequently asked questions

How do you check whether black granite has been dyed?

A cloth wetted with acetone is rubbed on an unpolished edge or the back of the slab. Dye or colour enhancer shows on the cloth. It is a screening check; a lab can confirm the treatment if needed.

Why do granite worktops crack at the sink cut-out?

The strip of stone beside a cut-out is narrow and carries stress during transport and fitting. Square inside corners concentrate it. Rounded corners and steel rods set under the strips reduce the risk; the inspector checks both.

Is mesh on the back of a granite slab a sign of poor quality?

Not always. Mesh and resin are common on stones with natural fissures. They should be agreed in the order, well bonded, and not hiding a crack through the slab.

How many granite slabs do you check?

Slabs are often checked one by one, because each is unique and costly. For tiles we use ISO 2859-1 sampling, usually General Inspection Level II, and open cartons from across the lot.

Know before it ships

Tell us the product, the factory's city and your ready date. We confirm the inspector, the notice time and the price before you book.

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Granite slab, tile and countertop inspection in India