Opal

Rainbow Ethiopian opal cut "Marquis".
The name "opal" comes from the Sanskrit word upala precious stone. Other names of the mineral and its varieties: Royal opal, harlequin, Girasol, Girasol, hydrofon, hyalite. Opal refers to precious stones.
Video in the blog post www.livemaster.ru/topic/3425592-blog-opal?inside=1&wf=0&vr=1
In jewelry used mainly the so-called precious opals that are different iridescent play of color is opalescent, which is typical of semi-transparent varieties.

Precious opal is of several types:
"white" - with translucent opalescence in light blue tones;
"black" - with shades of purple, blue, green, Burgundy and red flashes of an advantage;
"fire" - yellow or red with fiery reflections;
"Royal" - multicolor mosaic pattern and opalescence;
"Girasol" blue or colorless light red tones;
"lejos opal" - green with playing different shades of that color, and Carmine.