Cyprus Gemological Laboratory (CGL) | Diamond & Gemstone Certification, Nicosia

Welcome to Cyprus Gemological Laboratory (CGL)

The diamond industry is a global business and its growth in recent decades has been matched by the development of specialised gemological laboratories dedicated to the identification, grading and certification of diamonds using advanced technology.

The Cyprus Gemological Laboratory (CGL) is a modern gemological facility providing precise, high-quality testing and appraisal services to the diamond and gemstone market of the Eastern Mediterranean.

Our Gemological Standards & Online Verification

In line with international gemological practice, CGL certifies both natural and laboratory-grown diamonds, grading each on the 4Cs: carat weight, cut, colour and clarity. Every certificate clearly states whether the diamond is natural or laboratory-grown.

Every CGL certificate is a signed, detailed record of your gemstone based on rigorous scientific analysis, advanced laboratory instrumentation and the professional expertise of our resident gemologist. Each certificate is securely stored in our laboratory database and can be verified online.

All grading, identification and treatment findings represent the professional opinion of our gemologist at the time of examination. Results from other laboratories may differ due to differences in equipment, methods and examination conditions. Full terms are printed on each CGL certificate.

Trusted Regional Expertise

CGL provides a full suite of specialised services for the scientific identification, grading and valuation of loose diamonds, coloured gemstones and fine mounted jewellery.

Through our professional membership of the International Gem Society (IGS), our extensive gemological experience and our specialised testing equipment, CGL has established itself as a trusted regional gemological laboratory serving both private clients and the fine jewellery trade.

About Us

The Cyprus Gemological Laboratory (CGL) has served the diamond and gemstone market in Cyprus since 2000. Whether you are buying, selling, insuring or simply want to understand a stone you already own, knowing its true identity, quality and characteristics matters. A CGL certificate gives you a clear, documented record, prepared to internationally recognised grading standards.

The laboratory is equipped with advanced instruments, including Raman spectroscopy, an electronic gemstone spectrometer, UNOscope HD and short-wave and long-wave ultraviolet testing, allowing precise identification and grading of diamonds and coloured gemstones.

Our Gemologist

CGL is led by its founder, Aris Tsiropoulos, a gemologist with over three decades of experience and a lifelong commitment to professional education:

Coloured Gem Professional Diploma, Gübelin Academy, Switzerland (2024)
Professional Gemologist, International Gem Society (IGS), Member #103603 (2007)
Diploma in Diamantology, School of Diamantology, Cyprus (2001)
Certificate in Gemmology, Master Gem Gemmological Laboratory, affiliated with Gem-A, Great Britain (1997)
International School of Gemology certifications in coloured gemstones, gemstone treatments and laboratory-grown gemstones (2020)
Member of the organising committee, 5th Mediterranean Gemmological & Jewellery Conference, Cyprus (2019)

Through continuous study and professional membership of the International Gem Society, CGL stays current with the latest developments in gemstone identification, treatments and laboratory-grown diamonds.

Services

Diamond Certificate

A full gemological report on a loose natural or laboratory-grown diamond, covering its identification, the 4Cs, measurements and fluorescence.

Gemstone Certificate

Identification of a loose coloured gemstone, with a report of any treatments detected.

Jewellery Appraisal Report

A signed valuation document for diamonds, gemstones and mounted jewellery, prepared for insurance or estate purposes. An appraisal is separate from a certificate. From €80 per piece.

Verbal Assessment

An examination of your piece with the findings given verbally on collection: whether the diamonds are natural, what the gemstones are and the metal and its karat. No written report is issued and treatments are not assessed. From €30 per piece.

Laser Inscription

On request, inscription of a certificate number, personal message or logo on the girdle of a loose diamond or gemstone.

All services are by appointment. To book, call +357 22 518130 or email [email protected].

How to Submit a Stone

Contact us. Call +357 22 518130, send a WhatsApp message to the same number or email [email protected] to arrange your visit.
Bring your stones or jewellery to the laboratory. We list each item and give you a written receipt.
We examine your items. They remain with us at the laboratory and your documents are ready within 10 working days.
Collect your items and documents. Please bring your receipt.

If a stone needs further examination, we will call you to explain before going ahead.

If testing shows that a stone is synthetic, we will inform you before any certificate is prepared, so you can decide whether you still want one. If you choose not to proceed, a verbal assessment fee applies, from €30.

How We Examine a Stone

Certification

An independent, documented record of your stone.

A Cyprus Gemological Laboratory (CGL) certificate records the identity and quality of a diamond or gemstone, based on examination in our laboratory by our resident gemologist.

For diamonds, the certificate confirms whether the stone is natural or laboratory-grown and grades it on the 4Cs: carat weight, cut, colour and clarity. For coloured gemstones, it identifies the stone and reports any treatments detected.

A certificate describes the stone’s gemological characteristics; it does not state a price. If you require a monetary valuation for insurance or estate purposes, CGL can prepare a separate, formal appraisal document.

Every certificate is signed, stored securely in our laboratory database and can be verified at any time through our online system.

Identification

Natural, laboratory-grown or imitation.

CGL determines whether a stone is a natural diamond, a laboratory-grown diamond or an imitation.

This distinction matters because the differences cannot be observed with the eye alone. A laboratory-grown diamond has the same chemical composition and appearance as a natural diamond, while imitations such as cubic zirconia and moissanite are different materials made to resemble diamond. Laboratory testing is the only definitive way to distinguish them.

Testing relies on Raman spectroscopy, which analyses how laser light interacts with the stone to confirm its composition, alongside the laboratory’s other analytical instruments.

The result is stated clearly on every CGL certificate, providing clarity for buyers, sellers and insurers.

Colour Grading

Graded against master stones of known colour.

Colour is one of the 4Cs, alongside clarity, cut and carat weight, that define a diamond’s quality.

At the Cyprus Gemological Laboratory (CGL), colour is graded by comparing each diamond against a set of master stones of known colour. Diamonds are always graded loose, as metal settings can reflect light and influence the colour perceived by the eye.

Colour grading scale (colourless to light yellow or brown):

D, E, F: colourless
G, H, I, J: near colourless
K, L, M: faint tint, usually yellow
N to R: light tint, visible to the naked eye
S to Z: tint, usually yellow to brownish, visible even when mounted

Fancy coloured diamonds are evaluated according to separate standards.

Clarity Grading

An examination of a diamond’s internal and surface characteristics.

Clarity describes the presence, size and position of a diamond’s natural characteristics: inclusions within the stone and blemishes on its surface.

At the Cyprus Gemological Laboratory (CGL), each diamond is examined under a stereo microscope fitted with a digital camera, which records these characteristics.

Clarity grading scale:

FL, IF: flawless and internally flawless
VVS1, VVS2: very, very slightly included
VS1, VS2: very slightly included
SI1, SI2: slightly included
I1, I2, I3: included

Cut & Symmetry Grading

Precise measurement of a diamond’s proportions.

CGL evaluates diamond cut and symmetry with the UNOScope HD, an electronic grading system that combines a high-definition digital camera with high-speed measurement software.

The system measures round brilliant and many fancy-shaped diamonds against the standards used by leading laboratories, including GIA Facetware. It grades proportions and symmetry and detects extra facets.

Each evaluation records the diamond’s measurements, including weight, diameter, total depth, crown angle and height, pavilion angle and depth, and culet size.

Fluorescence Grading

How a diamond responds to ultraviolet light.

Some diamonds emit a visible glow, most often blue, when exposed to ultraviolet light. This reaction, known as fluorescence, is a natural characteristic of the stone and forms part of its documented identity.

At the Cyprus Gemological Laboratory (CGL), each diamond is examined in a dedicated ultraviolet chamber under both long-wave and short-wave light. We evaluate and record the intensity of the reaction using a standard five-step scale: None, Faint, Medium, Strong or Very Strong.

The fluorescence grade appears clearly on every CGL certificate.

Laser Inscription

A direct link between a stone and its certificate.

On request, the Cyprus Gemological Laboratory (CGL) can inscribe the certificate number of a diamond or gemstone on its girdle, the narrow outer edge of the stone, using the GEMScribe laser inscription system. The inscription is microscopic: invisible to the naked eye and readable under magnification.

This allows a stone to be matched to its CGL certificate at any time, which is valuable for identification, insurance and resale.

The same service is available for other inscriptions:

A personal message or special date
A serial number
A company logo or brand mark, for jewellers and the trade

Laser inscription is carried out on loose diamonds and gemstones only.

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