Lab-Grown Diamond Glossary: 40 Terms Explained Simply

Why a lab-grown diamond glossary helps

A lab-grown diamond glossary turns confusing listings into plain language. Once you know what terms like CVD, as-grown, VS2, girdle, HUID and making charges mean, you can compare quotes quickly, ask sharper questions and spot vague or misleading descriptions before you pay. Keep this page handy while you shop.

Jewellery listings in India mix gemmology, trade slang, hallmarking rules and brand marketing. A single product page might mention IGI, EF colour, VVS-VS clarity, 18KT, HUID, lifetime exchange and certified lab diamond in the space of a few lines. It is no wonder buyers feel lost.

We have grouped the terms by theme, from how stones are grown to how they are graded, set, sold and serviced. Each definition is short and practical, focused on what it means for your purchase rather than on technical detail.

Where a term relates to a policy, remember that terms typically vary by seller, so always read the specific policy rather than assuming the general meaning applies.

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Growth and origin terms

Lab-grown diamond: a real diamond created in a laboratory, with the same chemistry and crystal structure as a mined diamond. Also called laboratory-grown, lab-created, man-made or synthetic diamond. Natural diamond: a diamond formed in the earth and mined.

CVD, chemical vapour deposition: a growth method where carbon from a gas settles on a diamond seed in a vacuum chamber, building the crystal layer by layer. HPHT, high pressure high temperature: a growth method that recreates deep-earth conditions in a press, using a metal solvent.

Seed: the thin diamond slice or small crystal on which a lab-grown diamond grows. Rough: an uncut diamond crystal straight from growth or mining. As-grown: a lab-grown stone with no post-growth treatment detected. Post-growth treatment: heat or pressure applied after growth to change colour, often used on CVD stones.

Simulant: a material that imitates diamond but is not diamond, such as cubic zirconia, moissanite or glass. Moissanite: silicon carbide, a hard, fiery diamond alternative. Cubic zirconia or CZ: zirconium dioxide, an inexpensive simulant sold in India as American diamond or AD.

Grown diamond, cultured diamond and created diamond: alternative phrases you may see. They usually mean lab-grown, but ask the seller to confirm in writing. Mined diamond and earth-grown diamond: marketing phrases for natural diamonds.

Grading terms: the 4Cs

Cut: the quality of a diamond's proportions, symmetry and polish, which determines sparkle. Cut grades for rounds usually run Excellent, Very Good, Good, Fair, Poor. Ideal is a marketing term some sellers use for top proportions.

Colour: for white diamonds, the absence of colour, graded from D, colourless, through Z, light yellow or brown. D to F are colourless, G to J near-colourless. Listings sometimes give ranges like EF or GH for small stones.

Clarity: the presence of inclusions and blemishes, graded FL, IF, VVS1, VVS2, VS1, VS2, SI1, SI2, I1 to I3. Eye-clean means no inclusions visible to the naked eye at normal viewing distance.

Carat: a unit of weight, where one carat equals 0.2 grams. Total carat weight, often written ctw or TCW, is the combined weight of all diamonds in a piece. Cents or pointers: hundredths of a carat, so a 50-pointer is half a carat.

Report and certification terms

Grading report or certificate: a document from a laboratory describing a diamond's identity and grades. Labs widely used for lab-grown stones include IGI, GIA and SGL. In-house certificate: a grading card issued by the seller rather than an independent lab.

Report number: the unique identifier you can verify online on the lab's website. Laser inscription: microscopic text on the girdle, usually the report number and sometimes the words lab-grown.

Clarity plot: a diagram on the report showing inclusion locations. Fluorescence: the stone's glow under ultraviolet light, graded None to Very Strong. Comments: a report section noting treatments, growth method or other details.

Type IIa: a diamond with very little nitrogen, common in CVD stones and rare in nature. Jewellery certificate: a document covering a finished piece, often listing total diamond weight and quality range for small stones.

Lab-grown reports may carry slightly different wording from natural ones, such as Laboratory-Grown Diamond in the title. Some labs also issue digital reports linked by QR code. Whichever format you get, keep a copy with your invoice.

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Anatomy of a diamond

Table: the large flat facet on top. Crown: the upper part of the stone above the girdle. Girdle: the thin outer edge where crown meets pavilion, often inscribed. Pavilion: the lower, cone-shaped part that reflects light back up.

Culet: the tiny point or facet at the very bottom. Depth percentage: total depth divided by diameter. Table percentage: table width divided by diameter. These numbers help judge cut quality.

Spread: how large a stone looks from above relative to its weight. Bow-tie: a dark band across the centre of elongated shapes like ovals and pears. Length-to-width ratio: the proportion that describes how elongated a fancy shape is.

Facet: each flat polished surface. A round brilliant usually has 57 or 58 facets.

Setting and metal terms

Prong or claw: metal tips holding a stone. Bezel: a metal rim surrounding the stone. Pave: many small stones set closely together. Halo: a ring of small stones around a centre stone. Solitaire: a single prominent stone.

Melee: very small diamonds used as accents. Eternity band: a ring with stones all the way around. Tennis bracelet: a flexible line of individually set stones. Huggie: a small hoop earring that hugs the earlobe.

14KT, 18KT, 22KT: gold purity, where 24KT is pure. 14KT is about 58.5 percent gold, 18KT about 75 percent and 22KT about 91.6 percent. 925 sterling silver: 92.5 percent silver. PT950: 95 percent platinum.

BIS hallmark: India's official purity mark on gold jewellery. HUID: the six-character hallmark unique identification code, verifiable through the BIS Care app.

Rhodium plating: a thin layer of rhodium applied to white gold for a bright white finish, which wears over time and can be renewed. Two-tone: a design combining white and yellow gold. Nose pin, nath and mangalsutra are traditional Indian forms often now made with lab-grown stones.

Pricing and policy terms

Making charges: the manufacturing cost added to metal value, quoted as a percentage, per gram or flat. Wastage: a term some jewellers use for metal lost in manufacturing, often included in making charges.

GST: goods and services tax applied to jewellery, calculated on the total including making charges. Gross weight: total weight of the piece. Net weight: metal weight excluding stones.

Exchange: trading in a piece for credit against a new purchase. Buyback: selling a piece back to the jeweller for cash. Upgrade programme: exchange restricted to buying a higher-value piece. Terms typically vary by seller.

Return window: the period during which you can return a purchase. Lifetime warranty: a promise covering specific defects or services; read what it includes.

Festive offers: discounts during periods like Dhanteras and Akshaya Tritiya that may apply to making charges rather than metal or stone. Insurance valuation: a documented estimate of replacement value for insurance purposes, separate from resale value.

Terms to treat with caution

Some phrases sound reassuring but say little. Diamond-like, simulated diamond, AD diamond and diamond look describe simulants, not diamonds. Certified without a lab name may mean an in-house card. Eco or ethical without detail is marketing language.

When you see these, ask the seller to state plainly what the stone is, who graded it and what supports any claims. Clear answers are a good sign; vague ones are a reason to keep looking.

Using this glossary when you shop

Scan each listing for the key fields: stone type and origin, growth method or treatment if stated, 4Cs, lab and report number, metal purity and weight, making charges, GST and policies.

If any term is missing or vague, ask the seller to clarify in writing. Be cautious of listings that avoid stating lab-grown or that use simulant terms alongside diamond.

Save the report and invoice together, and note the HUID and report numbers in a safe place.

With the vocabulary in hand, you can shop like an insider and choose lab-grown jewellery with confidence.

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