Gemstone Glossary
Labradorescence
The play of colour seen in labradorite feldspar.
The phenomenon is caused by interference of very slightly out-of-phase light due to reflection from thin surfaces. Comparable to the colours seen on a film of oil on a water puddle.
Layered stone
Consisting of two differently coloured layers of agate. As naturally layered stones are extremely rared most layered stones are dyed. Used as seal stones for gemstone engravings
Lodolite
Lodolite is an unofficial tradename for quartzes with mineral inclusions belonging to the chlorite group. Depending on the type of chlorite the very attractive inclusions appear in various colours e.g. green, brown, orange, white, pink, purple etc.
The literal translation is "mud stone" (spanish lodo = mud).
We are not sure whether this name refers to the mining location in Minas Gerais, Brazil, or to the visual appearance of the inclusions.
Loupe clean
A term, originally only used for diamonds, only. A diamond is called loupe clean when a trained expert cannot detect any inclusions with the help of an aplanatic, achromatic 10x loupe. Diamonds with inclusions of a size of more than 5 microns must not be called loupe clean (including outer features e.g. "frazzles" at the girdle).
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