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Diamonds - An Introduction


Diamonds and their characteristic features


  • The word 'diamond' is derived from the Greek adamas, meaning 'invincible'.
  • The diamond is known as the 'king of gems' because of its exceptional brilliance, its reflection of light, its exceptional hardness and its rarity.
  • Rating 10 on the Mohs scale of hardness, diamond is the hardest known mineral, has the highest light refraction index and is regarded as the best conductor of heat.

Diamonds and their formation and surfacing

Diamonds form in the vast depths of the earth's mantel under very high pressure and at high temperatures. Diamonds are mined in the pipes of extinct volcanoes or washed out of accumulations of minerals, generally alluvial, known as 'placer deposits'.


Diamonds and their uses

Diamonds are highly coveted both as investments and as elements of jewellery. However, only around one-quarter of all diamonds mined globally are suitable as gemstones. Due to their extreme hardness, diamonds are also used for cutting and grinding tools for industrial use.
Diamonds are considered good investments, a view reinforced by rising prices for diamonds in recent years. RenéSim supplies diamonds at outstanding prices.

Go to Loose Diamonds


Treated diamonds

Treated diamonds are diamonds subjected to subsequent enhancement processes. A diamond is classified as untreated if it has only been altered by cutting or polishing. Enhancement enables its colour or clarity to be modified after cutting. RenéSim supplies only untreated diamonds, as treatment destroys the natural charm of a diamond. Treated diamonds must normally be designated as such and are generally available at lower prices since their raw material is of lower quality. RenéSim will only supply treated diamonds in response to specific enquiries.


Rough diamonds

It is not easy for individuals to obtain rough (uncut) diamonds. The uncut diamonds are generally sold directly to diamond cutters at the diamond exchanges. More about rough diamonds.


Famous diamonds

The most famous diamonds in the world include the 'Star of Africa', also known as 'Cullinan I', the 'Tiffany' and the 'Hope Diamond'. Read more about famous diamonds here.


Diamonds as an investment

Diamonds are also an extremely popular form of investment. Find out more here about opportunities for investment: Diamonds as an Investment.

Go to Investors' Corner


Quality characteristics - Diamonds and the Four Cs

1. Cut

The cut is the result of the process of cutting and polishing which gives a diamond its specific shape, and is the most important criterion to assess the quality of the diamond since it enhances the stone's brilliance and fire. Diamonds from RenéSim are in the categories Excellent, Very Good, Good and Fair. In the Excellent category, all light that enters the diamond is fully reflected.

2. Carat

Carat describes the weight of a diamond. One carat weighs 0.2 of a gram. The number of carats of a diamond does not directly reflect the size of the diamond, since the dimensions of the stone and the quality of the cut also apply as further criteria. Naturally, as a general principle the higher the number of carats of the diamond, the higher the price.

3. Colour

Over 90% of all diamonds have a yellow tint or hue. Diamonds are classified using a scale ranging from D to Z, in which D stands for the most colourless (whitest) diamond. Categories D to F are classified as colourless and categories G to J as near-colourless. Diamonds from category K onwards have an increasingly visible yellow tint. RenéSim only supplies relatively colourless diamonds in categories D to M. The more colourless ('whiter') a diamond is, the higher its value.

4. Clarity

Each diamond is a unique natural product and rarely completely ‘flawless’, or free from 'inclusions'. Flawless diamonds are extremely rare and correspondingly valuable. The official grading scale ranges from FL/IF (flawless) to P3 (obvious inclusions). RenéSim supplies diamonds in grades FL to SI2. In these categories inclusions are so small that they are invisible - or very rarely visible - to the naked eye.


Diamond cuts and shapes

Diamonds can be cut into a variety of shapes. Round brilliant-cut diamonds are the best-known; the brilliant cut is designed to create the maximum brilliance in a round diamond by reflecting the light to its best advantage. In addition to the brilliant cut, diamonds can be cut in the following ways: Princess (rectangular/square), Emerald, Oval, Pear (teardrop), Heart, Cushion, Asscher, Marquise and Radiant. Find out more about these Diamond cuts and shapes here.



All RenéSim diamonds are supplied with a certificate issued by an independent inspection body (e.g. GIA, HRD, IGI or EGL) that guarantees the authenticity of the diamond.


Further diamond characteristics


Diamond Drawing


The depth of a diamond designates the ratio between its height and diameter (height:width).


The table percentage of a diamond gives the ratio between the table (the central top facet) of the diamond and the total diameter (table:width). A table percentage of between 57% and 62% is generally regarded as optimum. Larger or smaller proportions impair the brilliance of the diamond.


The girdle of a diamond is the circumference between the upper and lower part of the cut diamond, and thus its widest part. The diamond should have a girdle that is neither too thin nor too thick.


The culet is the smallest facet at the bottom of a diamond. Ideally a diamond should come to a perfect point instead of having a culet. A culet that is too large may be visible as a black dot when the diamond is viewed from above, impairing the beauty of the stone.

Polish, Symmetry and Fluorescence


  • Polish: A diamond must be extremely finely polished to ensure no traces of the cutting process are visible on the surface and all corners and edges are crisply defined.
  • Symmetry: A diamond should have as uniform a shape as possible, with symmetrically arranged facets. The higher the symmetry of a diamond, the more brilliance it appears to have.
  • Fluorescence: A diamond may exhibit fluorescence to a greater or lesser degree, giving it a slight blue shimmer in the sun or under ultra-violet light. A diamond with strong fluorescence is generally of lesser value but may have its own individual charm.


For more detailed information on the subject of diamonds, why not browse our extensive Diamond Dictionary?


Choosing your diamond at RenéSim


  • Your options for choosing a diamond at RenéSim: Diamonds


You may also be interested in the following:

Are you interested in purchasing loose diamonds? We offer an extensive choice: up to 250,000 diamonds in our diamond database.

You may also like to examine the diamond rings and engagement rings in our Prêt-à-Porter Collection, in white gold, yellow gold, rose gold or platinum.

Our comprehensive Diamond Dictionary provides you with fascinating and useful information from the world of diamonds.

If you would like to purchase a diamond ring, we recommend our Ring Configurator: design your personal diamond ring.


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T +44 20 351 466 05

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As an online jeweller, RenéSim combines the benefits of a modern online-based business model with 180 years of family-run traditional craftsmanship in the jewellery industry. Gemstones such as diamonds are the central focus at RenéSim; we supply high-quality, thoroughly individual pieces such as engagement rings in addition to loose diamonds. We offer unique diamond post earrings, diamond rings, memory rings, engagement rings and much more. Consult the jewellery experts at RenéSim!

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