Is it easy to tell a fake opal?

[innerkitten]

I''ve noticed a huge range in pricing from $24.00 to $900.00 and figured some are just much better quality or some are fake or maybe both.

 

[mike04456]

Yes, there are ways to separate natural from synthetic from imitation opal (mainly magnification) but that and opal valuation are best left to the experts.

 

[valeria101]

Hi! At least someone takes some interest in all those colored stones!

This sounds like a story of doublets, triplets and solid stones... Opals (even the best qualities) often come out of the ground in thin layers, so the actual cabs get about 1-2 mm thin. In this case, the opal gets pegged to some support ( a layer of other stone or opal matrix, or...). This is called a 'doublet' and once in a bezel there is no way to see what happens under the layer of amazing color but the price goes way down. Triplets are even less opal (thinner layer) sandwiched between an opaque base and a clear top (such as synthetic white spinel, quartz or?). Triplets can be awesome looking since the upper layer of transparent stuff gives depth to the color play, but these are the cheapest.

To get a nice, larger solid opal (no backing, no nothing) especially with a dark (almost black) background and reddish color play is a rare sight and shocking financial mistake. The same thing as a doublet is somewhat affordable and towards cheap as a triplet. However, no opal with good color is cheap if large. Opals have grades too (like diamonds), but grading and pricing them is really no joke,

as mentioned above.

 

[Colored Gemstone Nut]

Telling Fake Opal Apart,




Natural Opal is a mixture of silica in water. Opal is formed by a very slow settling and hardening process.


The color you see is not in the stone, but rather the result of white light being split by microscopic prisms


or spaces between the various arrangements of silica particles.



A silica gel process was developed which duplicates nature. It involves three steps:

1. Creating microscopic silica spheres 2. Allowing the spheres to settle and harden in a controlled laboratory environment 3.Then subjecting the gelled material to a high pressure to form an opal.

Below I will list some physical & Optical characteristics which differentiate synthetic from Real Opal.

Natural opals have 5 to 15 percent of water, while synthetics do not.

Synthetic opals sometimes have a zirconium content, while naturals have barely any.

Synthetic opals are sometimes bound with epoxy, while naturals are usually not.

Polymer-impregnated manufactured opal. imitates the best opal, but it's not real opal, because it has 25 to 30 percent resin.

Gilson synthetic is easily identified by its snake skin appearance.(Under Microscope as Lawgem Pointed Out)

Glass imitations are easily identified by their coloration and varying Refractive Index.

Synthetics can be much lighter in weight (Specific Gravity)

Eveness & spread of fire and 'play of colour' are too perfect in some synthetics vs. naturals

There are 2 interesting sites I will reference for you about some additional in depth Opal Inormation...

www.kivits.com/opalvalues.html

www.yourgemologist.com/syntheticopal.html

Warm Regards......