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

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.

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.

Fluorescence Measurement

Radiation Measurement of the diamond using ultraviolet
Fluorescence UV / LW-SW Diamond Chamber

The Fluorescence is a characteristic that makes some diamonds appear to change color when they are exposed to the ultraviolet light that surrounds us every day in sunlight and in the light produced by fluorescent light bulbs. The Diamond Fluorescence refers to how a diamond responds when subjected to ultra-violet light. Some diamonds, when they are exposed to UV light, glow different colors.

CGL grades Fluorescence with 5 different ratings:
None
Faint
Medium
Strong
Very Strong

Laser Inscription

Code inscription on the diamond surface using laser for identification of the diamond with its certificate.

GEMScribe Diamond Girdle Laser Inscription:

GEMScribe is an automatic diamond laser inscription system which allows you to inscribe on the stone’s girdle for any conceived purpose, from branded inscription to personal dedications.

GEMScribe Diamond Inscription Application:
Brand your company logo.
Protect your diamond by inscribing a unique serial number.
Inscribe your customer’s personal message on the girdle of the diamond.
Inscribe even when the stone is already set on a ring.

Classification

Classification of diamond to I a and II a groups using Diamond Spotters and Diamond Illuminators for precise separation of the diamonds of the two groups.

Group A: type IaA, IaAB and Ib
Such colorless diamonds have not been decolorized by a HPHT treatment.
Group B: type IIa, IIb and rare IaB
Such diamonds may have been treated by a HPHT treatment.
If a diamond results in a type Ia no further investigation is done. If a diamond is type IIa then investigation for treatment HPHT takes place.
The diamond spotter initially has been developed as a reaction to the threat of the HPHT treated diamonds. You may test all diamonds with the diamond spotter. Be it colorless or colored, cut or rough crystal, loose or mounted. Even diamonds which are larger than the sample holder of the spotter may be tested.
Type II diamonds are found as colorless (type IIa), pink (IIa), blue (IIb) or brown (IIa and IIb) stones. Colorless, pink or blue stones may be naturally colored or the result of a High Pressure High Temperature treatment (HPHT).

Color Grades

Clarity measurement and color identification of the diamond with stereoscope equipped with Camera Discovery C30 “and “Diamond Master Sets “.

The Diamond color is one of four major characteristics that are considered when determining a diamond’s quality and value. They are known as the Four Cs, and the remaining three are diamond clarity, diamond cut, and diamond carat weight. Understanding these four characteristics, and how they interact, will help you choose a diamond that suits your tastes and your pocketbook. To be graded, diamonds must be loose, because once a diamond is set into metal the metal can affect the color we perceive.

Diamond Color Grades
Colorless diamonds and diamonds that are yellow or yellowish brown are grouped into the categories shown below. These grades do not apply to fancy colored diamonds – they have their own color grading standards.
D-E-F
Colorless
G-H-I-J
Nearly colorless
K-L-M
Faintly tinted, usually yellow.
N-O-P-Q-R
Lightly tinted, usually yellow. Tint can be seen with the naked eye.
S-T-U-V-W-X-Y-Z
Tinted, usually yellow diamonds, may progress to brownish.
Tint is visible to the naked eye, even when mounted.

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