Opals rough guide and worth
Opal is one of the most beautiful and enchanting gems on earth, mostly because of its origins, iridescences and lights.
There's a huge variety of opals in the world, depending usually on the colours, frailty and iridescence patterns, exactly like the 4 C's for Diamonds (Opals-Quality Factors of the Gemological Institute of America-GIA). The opal is composed of silica and water: when the water evaporates and precipitates at low temperatures to form layers or nodules of opal in fissures, veins, and cavities of volcanic and sedimentary rocks, it generates some silica deposits; it's a procedure that protracts during millennia as at the same time is very simple.
There's a huge variety of opals in the world, depending usually on the colours, frailty and iridescence patterns, exactly like the 4 C's for Diamonds (Opals-Quality Factors of the Gemological Institute of America-GIA). The opal is composed of silica and water: when the water evaporates and precipitates at low temperatures to form layers or nodules of opal in fissures, veins, and cavities of volcanic and sedimentary rocks, it generates some silica deposits; it's a procedure that protracts during millennia as at the same time is very simple.