A gem certificate (more strictly, a lab report or dossier) is a laboratory’s record of what a stone is and what has been done to it. It is not an appraisal — it states no retail value — and it is only as good as the lab that issued it. Reputable laboratories include GIA, Gübelin, SSEF, IGI, HRD and AGS, several with Asia-Pacific offices.

The lines that matter

Identity — the species and variety (natural sapphire, not just “sapphire”; laboratory-grown where applicable). Treatments — usually under comments: “no indications of heating” means untreated, and that phrase alone can multiply value; “heated”, “glass-filled” or “diffusion” each change the price band. Measurements and weight — dimensions in millimetres and carat weight, which together with the cut reveal proportions. Origin — some labs state geographic origin where the evidence supports it; it is opinion-grade and prized by collectors.

Reading between the lines

Comments carry the real story: phrases like “minor” clarity characteristics, “faint” colour zones or “pits on the table” describe what the grader saw. Two certificates with the same headline grades can describe noticeably different stones. Match the report to the stone: every report number can be checked online at the issuing lab, and the measurements must match your stone exactly.

Learning the system

Certificates, disclosure rules and treatment vocabulary are part of trade knowledge — covered in the gem and jewellery trade course at JDMIS, with the laboratory side of testing explained in how to get gemstones tested.

The birthstone tradition links one gem to each month, wearing “your” stone supposedly bringing luck or health. The modern list most jewellers use was standardised in 1912 by the American National Association of Jewelers and has been adjusted a few times since — which is why you will sometimes meet two stones competing for one month.

The modern list

January garnet · February amethyst · March aquamarine (bloodstone traditionally) · April diamond · May emerald · June pearl, moonstone or alexandrite · July ruby · August peridot (spinel added later) · September sapphire · October opal or tourmaline · November topaz or citrine · December turquoise, zircon or tanzanite.

Where it came from

The chain runs from the twelve stones of the High Priest’s breastplate in the Book of Exodus, through medieval associations of stones with months and zodiac signs, into Victorian sentimental jewellery and finally the trade standardisation of 1912. That history is why the list mixes precious gems (diamond, ruby, sapphire, emerald) with organics (pearl) and semi-precious material (garnet, amethyst) — it was never ranked by value.

Why jewellers like it

Birthstones give customers a personal, low-anxiety entry into gem buying: the choice is made for you, every budget has an option, and the gift story writes itself. The materials themselves — pearls, opals, the coloured stones — are covered in the gem-trade curriculum at JDMIS; see the gem and jewellery trade programme or browse the jewellery blog for individual stone stories.

Moissanite is the best-known diamond simulant of the current era, and the two are easily confused by eye — which is exactly why testers exist. The differences that matter are physical, visual and financial.

Origin and substance

Diamond is native carbon crystallised deep in the earth (or grown in a laboratory). Moissanite is silicon carbide — natural crystals are so rare that jewellery moissanite is essentially always laboratory-created. It is a distinct material, not a fake diamond any more than a ruby is a fake sapphire; both are gems, one simply carries the heritage and scarcity premium.

Hardness, fire and look

Diamond is the hardest natural material (10 on the Mohs scale); moissanite follows at about 9.25 — both stand up to daily wear. Visually, moissanite has higher dispersion, so it throws more coloured fire, especially in larger sizes; diamond’s appeal is its balance of brilliance and white sparkle. To most casual eyes the difference reads as “very sparkly” versus “classic”, and lighting decides who notices what.

Price and testing

A moissanite of the same apparent size costs a small fraction of a diamond of similar quality — the honest reason for its popularity. Thermal diamond testers, the shop standard, can be fooled by moissanite’s thermal conductivity; proper separation needs electrical-conductivity testing or professional instruments. For the trade-side view of simulants and synthetics — including the tester discussion with Presidium — see what tools gemmologists use; the material science is part of gem identification training at JDMIS.

Online, your photographs are the product. A well-made piece shot badly reads as a badly made piece, and the habits that fix this are simple enough for any maker to apply.

Light first

Jewellery is small, reflective and often faceted — three properties that punish bad light. Diffused, consistent light from two directions kills hard reflections on polished metal; a single hard light creates blown highlights that hide the very surfaces you polished. Daylight from a window with a thin white curtain is an honest starting setup; light tents and LED panels make it repeatable.

Focus and stability

At macro distances the depth of field is millimetres thin. Use a tripod or a brace, focus manually on the stone or the focal detail, and stop down for a little more depth. One perfectly sharp photo of the key detail outperforms ten soft overall shots.

Backgrounds, scale and honesty

Clean neutral backgrounds make colour and sparkle legible; a hand, wrist or neckline adds scale and desire. Shoot the same set of angles every time — front, side, on-body, detail, packaging — so your catalogue looks intentional and returns drop. Show flaws honestly in at least one frame: online buyers return what arrives as a surprise.

Going further

Lighting for metals and gems, styling and workflow are taught in the digital jewellery photography course at JDMIS — built for jewellers, not photographers — and the marketing side of using the images sits in the jewellery business curriculum at JDMIS.