How to Read a Gemstone Lab Certificate, Line by Line

A gemstone lab certificate tells you three things that matter most: what the stone is, whether it is natural, and whether it has been treated. Everything else, from weight to origin, either identifies the stone or adds an opinion. This guide walks through each section of a typical report, shows how to check it matches your stone, and lists the red flags. See also our lab-certified gemstones page and how we check authenticity.

Report first, certificate second

Most gemmological laboratories call their document a report, not a certificate, and the difference is worth understanding. A report describes the stone as the laboratory found it on the day it was examined. It does not promise a value, it does not cover anything done to the stone afterwards, and it is only as good as the laboratory that issued it. In Pakistan both words are used, and we use "certificate" on this site because that is what most buyers search for.

Keep two kinds of paper apart. A seller's own card, printed by the shop, is a description and a promise from that seller. An independent laboratory report is a third-party examination. Both can be useful, but only the second is independent.

The kinds of report you will meet

• Identification report: confirms the species and variety, says whether the stone is natural or synthetic, and comments on treatment. This is the report most buyers need.
• Origin report: adds the laboratory's opinion on the country or region the stone came from. It is usually a separate, additional service and is offered mainly for sapphire, ruby, emerald and a few others.
• Brief report or card: a wallet-sized version with fewer details. Useful, but read the full report if one exists.

Coloured stones are not graded on a fixed scale the way diamonds often are. Colour, clarity and cut are usually described in words rather than given a grade.

The header: report number, date and verification

Every genuine report carries a unique report number and an issue date. Many laboratories let you check the number on their website or by scanning a code on the report, and the online record should show the same weight, measurements and conclusions as the paper. If a report cannot be verified with the laboratory that issued it, treat it with caution.

Look at the photograph as well. It should show your stone, with the same shape, colour and visible features. A generic photo, or one that clearly shows a different stone, is a warning.

Weight, measurements and shape

These lines tie the report to one physical stone, so check them first.

• Weight is given in carats, usually to two decimal places. One carat is 0.2 grams. Weigh the stone on an accurate scale; it should match to within a hundredth or so.
• Measurements are given in millimetres as length, width and depth. Measure with a gauge or callipers; they should match closely.
• Shape and cut are described in words, such as oval mixed cut, cushion, or cabochon.

A stone that has been recut or repolished since testing will no longer match. A clear mismatch in weight or measurements means the report does not describe the stone in your hand, however genuine the paper itself.

Species and variety: what the stone is

A report names the mineral species first and the variety second. This is where Pakistani trade names and English trade names can cause confusion, because several familiar stones belong to the same species.

Trade name	Species on the report	Variety on the report
Neelam	Corundum	Sapphire (blue)
Pukhraj	Corundum	Sapphire (yellow)
Yaqoot	Corundum	Ruby
Zamurd	Beryl	Emerald
Beruj	Beryl	Aquamarine
Lehsunia	Chrysoberyl	Cat's eye
Sunehla	Topaz or quartz	Yellow topaz, or citrine

The last row matters. In the local market, yellow topaz and citrine are sometimes sold under the name Pukhraj, which properly means yellow sapphire. The report settles it: if the species line says corundum, it is sapphire; if it says topaz or quartz, it is not. Our Urdu and English gemstone names page lists more of these.

Natural, synthetic, imitation or composite

The next line tells you how the stone came to exist.

• Natural means formed in the earth.
• Synthetic or laboratory-grown means a real crystal of the same species, made in a factory. It has the same chemistry as the natural stone, which is why a laboratory is needed to separate them.
• Imitation or simulant means a different material made to look similar, such as glass for emerald.
• Composite means a stone made of parts joined together, for example corundum held together with large amounts of lead glass. These are sometimes sold as ruby.

Read this word carefully. A report that says "corundum" without saying "natural" deserves a second look at the rest of the document.

The treatment line: read it twice

The treatment comment often has more effect on value than anything else on the report. Common wordings include:

• No indications of heating or no evidence of treatment: the laboratory found no sign of the common treatments. For sapphire and ruby this is the most valued result.
• Indications of heating or heated: the stone has been heated to improve colour or clarity. This is widespread and stable. Some reports add a note on any residue left in fissures.
• Clarity enhancement with a degree such as none, minor, moderate or significant: standard on emerald reports, describing how much oil or resin fills the fissures.
• Diffusion: colour has been added by heating the stone with chemicals, sometimes only near the surface. It lowers value sharply.
• Lead-glass filling: fissures filled with glass to improve the look, common in low-cost ruby. Such stones need gentle care.
• Dyed, stabilised or irradiated: common on agate, turquoise and blue topaz respectively.

Some treatments cannot always be detected, and a careful report says so in its comments. "No indications" is an honest finding based on current methods, not an absolute guarantee.

Origin: an opinion, not a fact

If the report includes origin, read it as the laboratory's professional opinion. Laboratories form it by studying inclusions and trace elements and comparing them with reference stones. Some stones cannot be assigned to a country at all, and a report saying origin could not be determined is perfectly normal. For how origins differ in practice, see where blue sapphire comes from and our gemstone origins guide.

Colour, transparency and special effects

These lines describe appearance in words: for example "blue", "intense purplish red", "transparent", "translucent". Phenomena such as a star (asterism) or a cat's eye line (chatoyancy) are noted here too. They help you confirm the stone matches, but they are descriptions, not grades. Two laboratories may describe the same colour with different words.

The comments and the small print

Always read the comments box and the conditions on the back or at the foot of the report. This is where a laboratory notes things like possible further treatment, an inclusion that could affect durability, or the limits of its methods. The small print also usually states that the report is not a valuation and does not guarantee the stone against damage or later treatment.

Red flags on a certificate

• No report number, or a number the issuing laboratory cannot verify.
• Weight or measurements that do not match the stone.
• A photo that does not show your stone.
• No treatment line at all on a sapphire, ruby or emerald.
• Phrases such as "100% natural" or "guaranteed" with no species, treatment or method stated.
• A laboratory you cannot find any independent information about.
• A certificate offered as the reason a very low price is fair.

Our guides on real versus fake gemstones and buying a genuine gemstone in Pakistan cover the checks to make before you even reach the paperwork.

Which stones are worth certifying?

Testing makes the most sense where natural and synthetic stones look alike and treatment changes value: blue sapphire, yellow sapphire, ruby and emerald in particular, and also cat's eye. For common, inexpensive stones such as agate or jasper, the lab fee can be large compared with the stone, and a seller's clear disclosure is often enough.

How GemStore handles certificates

We sell natural stones only, never synthetic or lab-created, and we disclose known treatments. A certificate is available on request, and independent lab testing can be arranged on request, so a stone can be examined by a laboratory you are comfortable with before you rely on it. Ask us on WhatsApp before you order if you would like a stone tested. Cash on Delivery is available anywhere in Pakistan, you may inspect the stone before paying the rider, and returns are accepted within 7 days. For delivery charges, see our delivery details.

Shop the stones: sapphire · yellow sapphire · ruby · emerald · cat eye.