Fire opal is a transparent to translucent opal, with warm body colours of yellow, orange, orange-yellow or red. It does not usually show any play of colour, although occasionally a stone will exhibit bright green flashes. The most famous source of fire opals is the state of Querétaro in Mexico; these opals are commonly called Mexican fire opals. Fire opals that do not show play of colour are sometimes referred to as jelly opals. Mexican opals are sometimes cut in their ryholitic host material if it is hard enough to allow cutting and polishing.
Rounds: 2mm – 10mm
Oval: 4x3mm – 10x8mm
Pear: 4x3mm – 10x7mm
Marquise: 4x2mm – 10x5mm
Octagonal: 5x3mm – 8x6mm
Trillion: 3mm – 7mm
Heart: 5mm – 6mm
Square: 2mm – 5mm
Princess Cut: 4mm
A large selection of specimen single stones in both faceted and cabochon are available
Chemical Formula: SiO2 · nH2O (hydrous, silicon dioxide)
Crystal Structure: Amorphous
Colour: Yellow to orange, orange-red
Hardness: 5.0-6.5 on Moh`s scale
Refractive Index: 1.37 – 1.52
Specific Gravity: 1.98 – 2.25
Treatments: Amethyst quartz is typically untreated. Some amethyst stones may be enhanced though heating, but heating of amethyst will reduce colouring agent and result in ‘heated citrine’. Heating can remove unwanted brownish inclusions in some amethysts or lighten the colour of overly dark stones.
Care: Opals in general have a high level of water content. In fact, the water content can constitute up to 21% of its weight. This is the reason why opals are vulnerable to ‘crazing’ caused by dehydration. If an opal is allowed to dry, it will crack and fade. The drying will cause cracks and fissures that reach the surface. Always protect it from excessive heat and prolonged exposure to strong light which may dry out the stone.
Fire opal stones can be cleaned or rinsed under warm water with a soft clean cloth. Never use bleach, chemicals or any ultrasonic cleaners to clean your opal stone. The vibrations alone can cause an opal stone to crack.