achatopal
ball
cacholong
cobble
collection
crystal
crystalline
decorative
fire
fire opal
gem
gemmology
gemology
gemstone
geological
geology
green
isolated
kacholong
kalmuck agate
kascholong
milky
mineral
natural
nature
opal
ore
ornamental
pebble
perlmutteropal
perlopal
piece
pink
polished
porzellanopal
raw
rock
sample
set
specimen
sphere
stone
transparent
tumbled
tumbling
various
white
white background
yellow