Diamonds are the hardest known mineral on our planet, the extremely high light refraction are one of the unique distinguishing characteristics of a diamond.   The rough diamond is formed under high pressure and temperature resulting in the modification of carbon in crystalline form with a hardness of 10 on the Mohs hardness scale.   Derived from the Greek adámas, which means "unbreakable", it serves as an indication of their unique property: the hardness they possess.   Common occurrences of diamond crystals are octahedron and rhombic dodecahedron.

About 90% of all rough diamonds mined worldwide have irregular shapes. Depending on the usability, a distinction is made between Sawables, shapes, make Ables, Maclen, Flats, Cleavage and chips.

Diamonds vary in shape and size and, depending on the structure of the original volume, lose between 30-60% of its mass during the grinding process.

We distinguish:
• Periphery crystals: section parallel to the surface
• Feasible crystals: tuning the piece, usually without cleavage
• Forms: heavily distorted structures with high quality
• Snippets: Small material with lower quality
• Stretched and small. Crystals and raw material with inclusions, etc.

The better and more valuable the octahedral structure is, the smaller the abrasive loss. Today, diamond imitations are produced industrially. Here we speak of moissanite and cubic zirconia.  These imitation stones can however be distinguished from the real diamonds with various testing methods.