Production of Verneuil-synthetic spinel and corundum at Djeva SA in Monthey (Switzerland)
• Synthetic: Artificial (manufactured) stone with basically the same chemistry and structure as its’ natural counterpart.
• Imitation: Any stone that imitates the visual appearance of a natural gemstone (different chemistry and structure).
• An imitation can be either a cheaper natural stone, a treated or a synthetic stone, or even an artificial product without a natural counterpart (e.g. cubic zirconia).
| Synthetic spinel
light purplish pink Verneuil-synthetic spinel:
Numerous tiny inclusions.
Unexpectedly, this synthetic spinel contains no chromium. The colour is due to tetrahedrally coordinated Fe2+.
| Synthetic spinel
Vivid blue Verneuil-synthetic Cobalt-spinel:
Fine veils giving the stone a natural appearance.
Pure cobalt colour, no iron present !
| Synthetic spinel
Natural spinel
Flux-melt synthetic spinel
| Synthetic spinel
Natural spinel
Flux-melt synthetic spinel
| Synthetic spinel
Layout of flux-melt synthetic spinel analysed at SSEF.
• Such synthetic rubies are known for more than 15 years!
• with lab report claiming to be a natural ruby!
Synthetic ruby (flux-melt) of 4.27 ct
| Synthetic corundum
Natural ruby from Vatomandry (Madagascar) with numerous zircon clusters
Flux-melt synthetic ruby with similar clusters, however they are not zircons!
| Synthetic corundum
Flux-melt synthetic ruby of 6 ct with lab reports as natural ruby!
| Synthetic corundum
Orange residues could be misinterpreted as iron hydroxide, but is flux residue from Ramaura synthesis process.
| Bad surprises for our client
Necklace containing about 50 flux-melt synthetic rubies
Due to the presence of many inclusions, an unexperienced gemmologist may consider them to be heated but natural.
| Even worse…
Jewellery containing heated Verneuil synthetic rubies and natural diamonds
An unexperienced gemmologist may consider them to be heated and flux-filled natural stones.
| Synthetic emerald
Flux-melt synthetic emerald grown on natural beryl crystals
• Research experiments (Russia).
• Easy to detect for experienced gemmologist/mineralogist
• Many small platinum flakes at surface and within synthetic emerald layer.
Deep green flux-melt synthetic on-growth.
heavily included low quality whitish beryl
| Synthetic alexandrite
flux-melt synthetic alexandrite
• Visually similar to Russian alexandrite.
• Full of tiny inclusions resembling natural alexandrite.
• Detection only after careful microscopic observation and spectroscopic and chemical analysis.
Platinum flakes from crucible
Flux residues in healed fissures
| Melée testing (coloured stones):
Batch of small flux-melt synthetic rubies recently analysed at SSEF.
| Melée testing (coloured stones):
Synthetic ruby mixed in a batch of calibrated rubies.
| Melée testing (coloured stones):
• Usually very small stones (1-4 mm).
• Often submitted in larger batches.
• Calibrated or specifically designated cut for a specific place in the setting.
• Contain often no or only very few inclusions.
| Melée testing (coloured stones):
• Testing requires analytical protocol specifically adapted for each colour variety.
• Time-consuming, requires often highly advanced methods (e.g. Raman and LAICPMS).
• Unfortunately, this testing can not be done just for few pennies…
Beryllium in melée size fancy sapphires
https://www.brilliantearth.com
https://www.mevisto.com
Curved banding of Verneuilsynthetic sapphire!
https://anabelachan.com
• Identification of synthetic coloured stones is usually quite straightforward.
• Even detectable for an experienced dealer.
• Few cases need advanced analytical methods. These stones may come with reports calling them ‘natural’.
• Melée size coloured stones can be separated (natural vs. synthetic), however this requires adapted testing methods and is often challenging (quantity and small size).
• Correct labelling is mandatory for synthetic stones (synthetic, lab-grown, lab-created) and imitations. A synthetic stone cannot be called gemstone (CIBJO)!
• Trade organisations and consumer protection agencies need to ensure correct labelling.
• Gem labs support by detecting synthetic stones and by using clear wording on reports.
