Reading a Gemstone Lab Certificate: A Section-by-Section Guide

Of everything on a gemstone lab certificate, three things matter most: what the stone is, whether it is natural, and whether it has been treated. The rest either pins the paper to one particular stone or adds an opinion, such as origin. Below we go through a typical report section by section, show you how to check it really belongs to your stone, and list the warning signs we look for. Our lab-certified gemstones page and how we check authenticity are useful alongside this.

A report, not a guarantee

Most gem labs call their document a report rather than a certificate, and the difference is worth knowing. A report describes the stone as the lab found it on the day it was examined. It does not state a value, it says nothing about anything done to the stone afterwards, and it is only as good as the lab behind it. In Pakistan people use both words, and we say "certificate" on this site because that is what most buyers search for.

Keep two kinds of paper separate in your mind. A card printed by the shop itself is that seller's description and promise. An independent lab report is an examination by a third party. Both have their uses, but only the second is independent.

Types of report you will come across

• Identification report: confirms species and variety, says whether the stone is natural or synthetic, and comments on treatment. This is what most buyers need.
• Origin report: adds the lab's opinion on which country or region the stone came from. It is usually an extra service, offered mainly for sapphire, ruby, emerald and a handful of others.
• Brief report or card: a wallet-sized version with less detail. Handy, but read the full report if there is one.

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

The top of the report: number, date and verification

A genuine report always has its own report number and an issue date. Many labs let you check that number on their website or by scanning a code printed on the report, and the online record should show the same weight, measurements and findings as the paper. If you cannot verify a report with the lab that supposedly issued it, be careful.

Look at the photo too. It should be your stone, with the same shape, colour and visible features. A generic picture, or one that obviously shows a different stone, is a warning.

Weight, measurements and shape

These lines tie the paper to one physical stone, so check them before anything else.

• Weight is 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 about a hundredth.
• Measurements are in millimetres: length, width and depth. Check them with a gauge or callipers; they should match closely.
• Shape and cut are given in words, such as oval mixed cut, cushion or cabochon.

If a stone has been recut or repolished since it was tested, it will no longer match. A clear difference in weight or measurements means the report is not describing the stone in your hand, however real the paper is.

Species and variety: what the stone actually is

The report gives the mineral species first, then the variety. This is where our local trade names and the English ones can get tangled, because several stones we know by different names are the same species.

That last row is important. In the bazaar, yellow topaz and citrine are sometimes sold as pukhraj, which properly means yellow sapphire. The report settles the matter: 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 pairs.

Natural, synthetic, imitation or composite

This line tells you how the stone came to exist.

• Natural means it formed in the earth.
• Synthetic or laboratory-grown means a real crystal of the same species, made in a factory. Its chemistry matches the natural stone, which is exactly why you need a lab to tell them apart.
• Imitation or simulant means a different material made to look alike, such as glass for emerald.
• Composite means a stone built from parts joined together, for example corundum held together with a lot of lead glass. These are sometimes sold as ruby.

Read this word slowly. A report that says "corundum" but never says "natural" deserves a closer look at everything else on it.

The treatment line: read it twice

The treatment comment often affects value more than anything else on the report. Wordings you will see include:

• No indications of heating or no evidence of treatment: the lab found no sign of the usual treatments. For sapphire and ruby this is the result buyers value most.
• Indications of heating or heated: the stone was heated to improve colour or clarity. Very common and stable. Some reports add a note about residue 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 cracks.
• Diffusion: colour added by heating the stone with chemicals, sometimes only near the surface. It cuts value sharply.
• Lead-glass filling: cracks filled with glass to improve the look, common in cheap ruby. These stones need gentle handling.
• Dyed, stabilised or irradiated: typical for agate, turquoise and blue topaz respectively.

Not every treatment can always be detected, and a careful lab 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 states an origin, read it as the lab's professional opinion. Labs reach it by studying inclusions and trace elements and comparing them with reference stones. Some stones cannot be placed in any country, and "origin could not be determined" is a perfectly normal result. 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 the look of the stone in words, for example "blue", "intense purplish red", "transparent" or "translucent". Effects like a star (asterism) or a cat's eye line (chatoyancy) are recorded here as well. They help you confirm the stone matches, but they are descriptions, not grades, and two labs may use different words for the same colour.

Comments and small print

Always read the comments box and the conditions on the back or at the bottom. That is where a lab notes things like possible further treatment, an inclusion that might affect durability, or the limits of its testing. The small print also usually says the report is not a valuation and does not protect the stone against later damage or treatment.

Warning signs on a certificate

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

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

Which stones are worth testing?

Lab testing earns its fee where natural and synthetic stones look alike and treatment changes the value: blue sapphire, yellow sapphire, ruby and emerald above all, and cat's eye as well. For common, inexpensive stones like agate or jasper, the lab fee can be large next to the price of the stone, and a seller's clear written disclosure is often enough.

How Authentic Gems approaches certificates

We sell natural stones only, never synthetic or lab-created, and we state known treatments on every listing. If you want a stone examined by an independent lab you are comfortable with before you rely on it, message us on WhatsApp before you order and we will talk it through with you. We deliver across Pakistan, with Karachi orders usually arriving in 1 to 2 working days and Lahore, Islamabad and other major cities in 2 to 4. With Cash on Delivery you can inspect the stone before paying the rider, and unused stones can be returned within 7 days. Delivery is a flat Rs. 500 per order; see our delivery details.

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