A   B   C   D   E   F   G   H   I   J   L   M   N   O   P   R   S   T   V   Z   ALL

zoning
also colour zoning; growth-related patchy or striated colour distribution within a gemstone. common in quartz and sapphire; no longer a sure sign of genuineness as some synthetic gemstones may also display colour zoning

  A   B   C   D   E   F   G   H   I   J   L   M   N   O   P   R   S   T   V   Z   ALL