Iren Diamonds Gemstone Report

A Iren Diamonds Gemstone Report is issued for a single loose gemstone. Gemstone Reports are issued only for natural stones (no synthetic or imitation material) and contain:

  • Weight
  • Shape and Cut
  • Measurements
  • Colour
  • Identification
  • Comments concerning the treatment situation
  • Colour photo of the stone

Our highly qualified experts

  • Hristofor Penshev Valkov ( IGI DIPLOMA)
  • Arkadiy Riys (ARDI Group)

Special characteristics, either natural (like asterism, colour change etc.) or induced by a treatment (like traces of treatments, significant damage etc.) may also appear under "comments".

The Iren Diamonds laboratory keeps the CIBJO Nomenclature Recommendations as guidelines for its Reports. These rules classify gemstones as minerals. Synthetic crystals, in contrast, are not considered gemstones, and their name must be always preceded by the word "synthetic".

When we identify "emerald" on our reports, it means that the stone is of natural formation. It is not our standard to use terms like "natural, genuine or precious" when we give the identification.

On request and under favourable conditions, we may put our opinion of the geographic origin of the gemstone, under comments. The determination of origin requires additional analytical tests and is thus a supplementary service.

The price of our service you can find here.

Colour grade:

The colour grade of a diamond is defined by comparing it with a CIBJO masterstone set (C2) and with two additional Iren Diamonds masterstone sets for better accuracy. The colour grades issued on diamond reports are:

Colour grade
Colour grade

Clarity grade:

The clarity grade is technically graded according to the CIBJO rules:

Clarity grade

Cut grade:

The cut grade of a diamond depends on its symmetry, polish, proportions and girdle thickness.

Cut grade 1 Cut grade 2
  • Gemstone Color Chart

The standard way to organize gemstones is by gem species (corundum, beryl, quartz, etc.) and variety (ruby, sapphire, topaz, spinel, etc.).

But for gemstone and jewelry collectors it is sometimes useful to organize gems by color. It provides a different overview of the gemstone world, and can be a timely reminder of the rarity of certain colors, such as red and blue.

Since there is enormous variation in color across the many gem varieties, we have organized this chart around color families. We have also included sections for multicolor, color change and star/cat's eye gems.

  • Red Gems
Burma Ruby Red Spinel Rhodolite Garnet Rubellite Tourmaline
Rhodonite Red zircon Cuprite  

Red is one of the rarest colors in the gems world, and a pure red, such as the famed pigeon's blood ruby, is exceptionally rare. Most red gems are orangey-red (spinel), pink-red (spinel, garnet) or purplish-red (rubellite tourmaline).

  • Blue Gems

Though blue is a more common gem color than red, very few gems occur in a pure saturated blue. Sapphire is really the only example, though tanzanite sometimes comes close. Other blue gems tend to be a grayish-blue (spinel, benitoite), greenish-blue (zircon, apatite, tourmaline, gem silica) or a pastel blue (aquamarine, topaz).

Blue Sapphire Tanzanite Blue Spinel Aquamarine
Blue Zircon Blue Apatite Color Change Fluorite Benitoite
Blue Topaz Paraiba Tourmaline Gem Silica Blue Tourmaline
  • Green Gems

Green presents the most choices in the gems world, but many of the finest green gems, such as emerald, jadeite, tsavorite garnet and demantoid garnet, are quite rare. Green hues are mainly due to traces of chromium and vanadium or iron.

Emerald Tsavorite Garnet Chrome Tourmaline Demantoid Garnet
Chrome Diopside Peridot Sphene Idocrase
Prehnite Green Tourmaline Jadeite Jade Green Sapphire
Mali Garnet Chrysoberyl Actinolite
Cat's Eye
Chrome Chalcedony Amblygonite Apatite Green Quartz
Green Fluorite      
  • Pink Gems

The finest pink gems are sapphire, spinel and tourmaline, with tourmaline exhibiting the widest range of pink hues. Kunzite and morganite are popular because they are relatively inexpensive and can be found in large sizes.

Pink Sapphire Pink Spinel Pink Tourmaline Kunzite
Morganite Pezzottaite Padparadscha Sapphire Rhodochrosite
  • Yellow/Gold/Bronze Gems

The most valuable yellow or gold gems are sapphire and imperial topaz. Citrine and yellow beryl are quite attractive, but relatively common. Yellow tourmaline is rare.

Yellow Sapphire Yellow Beryl Yellow Tourmaline Honey Zircon
Citrine Yellow Fluorite Scapolite Sphene
Imperial Topaz      
  • Orange Gems

Spessartite garnet is considered the finest of the vivid orange gems, but a number of other gems can be found in shades of orange, including sapphire, spinel, tourmaline and mexican fire opal.

Orange Sapphire Spessartite Garnet Orange Tourmaline Imperial Topaz
Citrine Orange Spinel Mexican Opal Sphalerite
Padparadscha Sapphire Rhodochrosite    
  • Violet/Purple Gems

There are relatively few violet or purple gems. Amethyst is the most famous and by far the most popular for jewelry. Sapphire and spinel can sometimes be found in violet, while chalcedony typically occurs in a greyish-lilac color.

Amethyst Purple Fluorite Chalcedony Scapolite
Violet Sapphire Purple Spinel Jeremejevite  
  • White/Colorless Gems

Diamond is the hardest and most valuable of the colorless gems, but a number of other gems have been popular over the years as alternatives, particularly white sapphire, white zircon, goshenite (white beryl), petalite and danburite.

Diamond White Sapphire White Zircon Goshenite Beryl
Petalite Danburite White Tourmaline Moonstone
  • Multicolor Gems

Some unusual gems displays regions of different color, notably the bi-color and tri-color tourmalines and the purple/gold quartz known as ametrine. Opal is famous for its play of color.

Bi-Color Tourmaline Ametrine Precious Opal Multicolor Fluorite
  • Color Change Gems

Some rare gems change color under varying lighting conditions. Alexandrite is the most famous example of a color change gem, displaying green or brown under daylight and a purplish-red under incandescent light.

Color-Change Alexandrite Color-Change Sapphire Color-Change Garnet Color-Change Diaspore Color-Change Fluorite
  • Star and Cat's Eye Gems

The phenomena of asterism (the star effect) and chatoyancy (the cat's eye effect) have been known for centures, and these rare gems are coveted by collectors. Star sapphires and star rubies are the best known gems that can display a star, while cat's eye chrysoberyl is the most famous cat's eye gem.


Authentication of natural origin and colour:

The following scientific instrumentation are used routinely: FTIR (identification of diamond type), low temperature photoluminescence spectrometry (colour authenticity test), low temperature UV-Vis spectrometry (treatment detection). Cut and shape are reported in accordance with the usual trade names.

Other items stated on Iren Diamonds Diamond Reports are:

  • Measurements
  • Proportions
  • Symmetry and Polish
  • Properties of the girdle (thickness, polish, and finish)
  • UV-fluorescence

a) Internal graining is considered as an internal growth characteristic, thus is not taken into account to downgrade a diamond from loupe clean to a lower grade.
b) Extra facets and naturals are the main external characteristics. If such characteristics are present in the stone, they are mentioned under comments.
c) Laser drilled diamonds are graded, but the laser drilling is mentioned under comments.

All red marks plotted on the diagram characterise internal features. All green marks plotted on the diagram characterise external features (mainly extra facets and naturals). According to CIBJO rules, diamonds with fissure treatments (Koss, Yehuda etc.) are not graded. Diamonds with a reduced colour (high-pressure high-temperature treated diamonds) are disclosed as Treated Diamonds.