Chatham synthetic Ruby357 viewsInternal diagnostic features include various forms of flux residue (opaque white globules, mesh-like patterns and tightly arranged white fingerprints); platinum platelets (hexagonal, triangular, rectangular and spiky) which reflect light with a silvery lustre; thick angular platinum crystals; white cloud-like areas (composed of a dense concentration of minute particles); transparent crystals; hammock-shaped and net-like intertwined feathers; and colour zoning.
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Kashan synthetic Ruby358 viewsThe Kashan synthetic ruby has been back in the market after many years of absence.
In the early 1960s stones it was possible to identify traces of the seed crystal within the gem. Feather-like structures similar to those seen in synthetic flux-fusion emeralds, and a dot-dash pattern of droplet-like inclusions were often present. These stones sometimes contained inclusions that resembled the marks made when a loaded paint brush is slapped on a wall (the so-called "paint splash" inclusions).
The later 1970s Kashan rubies often contain solidfilled, coarse negative crystals (which contain a granular or sugary material and have a high degree of reflectivity); clusters of parallel, rod-like, solid-filled negative crystals; wispy patterns resembling rain drops ("rain" or "dust" inclusions); and rain-like structures resembling comets.
Silk is rarely present, and then only appears as single, isolated filaments or needles. The presence in a stone of significant quantities of silk is evidence that the ruby is not a Kashan.
Because Kashan rubies contain varying amounts of iron oxide, their S.W. U-V transmission factors overlap those of natural rubies. The colour of most Kashan rubies is reasonably close to that of many Thai rubies, and in comparing the two, it's worth noting that most Kashans show a stronger orange dichroism than Thai rubies.
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Ramaura synthetic Ruby338 viewsThese stones are manufactured by JO Crystal Company in California. Inclusions consist of various forms of flux, particularly coarse orange-yellow flux and white flux "fingerprints".
These features, together with colour zoning, "comet tail" inclusions and conically shaped feathers can provide conclusive proof of synthesis. Another identifying hallmark of the Ramaura ruby is the parallel graining or growth lines, also described as the "Scotch in water" or "heat wave" effect.
What may, however, prove to be the main identifying feature of the Ramaura ruby is its fluorescent zoning under L.W. U-V; the manufacturer claims to have introduced a rare-earth dopant to make the stone more easily identifiable when exposed to U-V.
This fluorescent zoning occurs in thin areas just below the surface. It varies from intense to very intense, and has a colour that ranges from distinct sulphur yellow through yellowish orange to a nearly pure orange. Although generally quite thin, these zoned areas also possess a dull; chalky translucent appearance. Unfortunately, some cut stones have been seen that don't possess this tell-tale fluorescence.
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Ruby, natural, Thailand384 viewsIn Thai rubies, one of the characteristic inclusions consists of a core with rings around it ("Saturn" inclusion) or a fingerprint pattern that either cuts through the core's centre or rests against it. If there are several Saturn inclusions, they all tend to be orientated parallel to each other.
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Ruby, natural, Thailand369 views
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Linde synthetic Star Ruby342 views
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Knischka synthetic Ruby333 viewsDeveloped by Prof. P.O. Knischka, this synthetic ruby is recognizable in the rough crystal by its spindleshaped, multi-facetted shape. Facetted stones (these aren't yet widely distributed) may contain phantom-like clouds of dust particles (similar to those seen in Burma rubies).
Other more diagnostic internal features include swirls of colour; irregularly shaped, net-like liquid feathers; parallel negative crystals having- the same bipyramidal habit as the host crystal and appearing at the end of long crystal tubes; black, distorted hexagonal platelets of platinum and silver; and two-phase inclusions (with ill-defined void boundaries and conspicuous bubbles), this last feature being regarded as an identifying characteristic of Knischka rubies.
When visible on a spectroscope, an absorption band between 250 and 400 nm is a clear indication that the ruby is a synthetic (this band is more easily detectable on a spectrophotometer). The Knischka rubies that have been inspected so far show little iron content, and therefore have a high S.W. U-V transmission factor.
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Lechleitner synthetic Ruby340 views
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Lechleitner synthetic Ruby329 views
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Ruby, natural356 views
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Ruby, natural, Africa355 views
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Curved striae in synthetic ruby447 viewsCurved striae in synthetic ruby, seen under diffused lighting.
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