Opals: Known as the QUEEN of all gemstones.  

Australian Lightning Ridge Blacks [ N-1 to N4], Darks [N-5 and N-6], and Australian Crystals [N-7 to N10) are absolutely some of the most valuable and "Best" found in the opal world.

Note: The Lightning Ridge Dark Opals are sometimes known as Grey's or even mistakingly called Semi-Blacks in the market place.

Natural Hydrophane Opals mined from Africa (Ethiopian) can have great color and fire for the price.  The Ethiopian Fire Opals are bright orange and a few have very good multiple colored flames.   The Mexican fire opals can sizzle with orange or yellow internal flames!