How to Read a Stone Slab: Veining, Fill, and What to Watch For

The Difference Between "Character" and "Defect"

Natural stone is, by definition, imperfect. Veins, fissures, pitting, fill, and colour variation are intrinsic to the material. Learning to distinguish desirable natural character from actual defects is a fundamental sourcing skill.

Understanding Veining

• Open veins (fissures) — Run your fingernail across the vein: if it catches or the vein is recessed, it's a true fissure. These can be reinforced with epoxy.
• Filled veins — Filled with polyester or epoxy at the factory. Look for sheen differences under raking light.
• Stress cracks — Hairline fractures that may affect structural integrity in countertop applications.

How to Inspect for Fill

Inspect the slab under strong raking light (side-lit, parallel to the face). Run your palm across the surface — good fill should be flush. For travertine: confirm whether the slab is "filled" or "unfilled" — this is a specification choice, not a defect.

Colour Variation and Lot Matching

For a large project, book sufficient quantity from the same production lot in one purchase. Request slab photos or video of the actual slabs you'll receive — not stock images. LithoPrime vendors can share slab-specific photos and video directly through the messaging system.