[weekly-gems]

Today's gem:

Diamond

Formula: C

Color: Colorless, yellow, cognac, brown, champagne, or black; less commonly other colors.

Hardness: 10

The hardest natural substance known, named after the Ancient Greek adamas (diamond). Few types of impurity can contaminate it, and the high refractive index, fluorescence and dispersion makes it very prized. Diamonds are the birthstones of April and historically said to bring victory and protection against insanity, diseases and enchantments. These gems are also associated with weddings and marriage.

Representation on media:

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[weekly-gems]

Today's gem:

Lapis Lazuli

Formula: Na7Ca(Al6Si6O24)(SO4)(S3) · H2O from lazurite, FeS2 from pyrite, CaCO3 from calcite, and CaMgSi2O6 from diopside

Color: Mainly blue (from lazurite), white (calcite) and metallic yellow (pyrite)

Hardness: 5.5

A metamorphic rock composed primarily of lazurite and various other minerals; it's name is from the Latin lapis (stone) and the Persian lazhward (blue). It has been used throughout the centuries as a semi-precious stone and crushed into powder to produce the ultramarine pigment. In Ancient Egypt, this stone was used in amulets and ornaments and in Ancient Rome, associated with royalty.

Representation on media:

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[weekly-gems]

Today's gem:

Phosphophyllite

Formula: Zn2Fe 2+(PO4)2 · 4H2O

Color: Blue-green - colorless

Hardness: 3 - 3.5

A gem named after it's composition (phosphate) and physical structure (the Greek phyllos, leaf), referring to it's perfect cleavage. It's prized by mineral collectors, but not used in jewellery because of it's brittleness.

Representation on media:

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