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Lab Notes

Russian Demantoids!


The laboratory had the pleasure to do a photographic study on a fine collection of Demantoid garnets from the classic Russian Ural mountains tract. This deposit has long been lauded for some of the finest colors of demantoid ever produced. Although the yield from this famed locale has slowed to a trickle these stones still trade and come to market through numerous second-hand sources.


Inclusions are part of the process for accurately identifying geographic origin of gemstones. Positive origin identification can greatly enhance the value of a gem. Famed locations command a premium and trusted laboratory certificates are the best means of assuring that a gemstone is indeed from the purported mine.


These fabulous specimens all show the telltale horsetail inclusion indicative of this garnet variety. The below photomicrographs are magnified 45X, 10X and 15X respectively. They also illustrate the different forms this inclusion can take. It is particularly exceptional to see curvilinear material crystalized inside a host crystal and that's what makes us so excited about these exceptional specimens!


More detailed study of these stones can be found in the PGSL Gemstones 200 course book.

Buzz....what's trending in the lab and market place                             


- We see a growing trend in traditional wedding jewelry through plain or fashion gold wedding bands. Younger eco-conscious brides are looking to make this union by shopping for responsible brands in pure "virgin" gold (conflict-free).  In the diamond wedding sets the white metals still outsell yellow, but pink is finding its rightful place. 

- Coral, Jadeite, Opal and fancy color Diamonds are strong sellers.  Freshwater Pearls sales are strong, requests for fine South Sea pearls are strong, in the last year or so prices have gone up 15-20%, and supply for high quality is not abundant.


- Many buyers still pay more attention to brand names than to design.   

- Jewelry has made it to the level of being a staple fashion accessory that enhances your wardrobe and personality, just like a purse or shoes.  Rings, earrings, and bracelets in all forms, from precious metals to composite material, set with or without gems, or other organic materials.  No longer is silver jewelry frowned upon; big and chunky is in.  Inexpensive to very expensive sets of parures are back.  Fashionable knuckle or multi-finger rings are in, and funky earrings with ear-climbers or ear-cuffs are not falling on deaf ears. Lots of high end and commercial quality gemstones are used as accents as well as headline pieces.


- Couture, JCK, and the Antique Jewelry & Watch shows are behind us, as is the Hong Kong show. On average, exhibitors and buyers alike seem a bit more optimistic about this year's business. Of course you have the same people who always complain, but the US and EU have been steadily improving. The new norm is coming into its own with a constant modest growth. China is still the leading contender, and with the lower classes developing into the middle class they see loose diamonds as good for investment as well as for classic, traditional diamond jewelry. GIA is benefiting [or suffering] from this surge, as they are grading thousands of 0.30-0.50 pointers. It reminds me of the late 1960's when Japan was introduced to diamond engagement rings by J. Walter Thompson's ad agency. In little more than a decade, a fifteen-hundred-year tradition of courting rituals was transformed as young couples chose instead the romance and esteem of diamond engagement rings. Diamonds became a staple of the Japanese marriage and Japan became, after the United States, the second largest market for the sale of diamond engagement rings.


Myriam Tashey

Vintage Coral Earrings and 15mm South Sea Pearl Earrings 

Fine Sapphire & Diamond Parure submitted to the laboratory

Jeweler Spotlight

Featuring Christopher Duquet Fine Jewelry Design 


    Christopher Duquet is a jewelry designer in the city of Evanston. His shop produces one of a kind and limited edition works of fine jewelry. Christopher has won several national awards for design and is currently working on a new series scheduled to debut this fall called Facing East.   


    This collection is inspired by ancient Edo (modern day Tokyo) that became renowned for its artistic achievements in painting, print making, and culture. The "Ukiyo" period (1600-1867) produced works of such gracefulness and beauty that the feeling of this style became an inspiration and challenge to translate into modern, wearable art.


    The collection is in its first phases, but a couple of pieces have become Christopher's favorites. Shown to the right are two pairs of earrings. The "Spirit House" drops with black pearls and diamonds were based on the Shinto shrine form, and the "Japanese Flowers" buttons were inspired by the woodblock prints of nature, in particular flowers.


More information at: 

A Photographic Study of HPHT Synthetic Diamonds


Author: Eitan Tashey


PGS Laboratory recently completed a study of lab-grown fancy yellow and orange diamonds grown and manufactured by the Gemesis Corporation. The findings produced a more comprehensive understanding of the HPHT process as the staff was able to identify numerous features that were characteristic to these stones. The following photomicrographs illustrate some of the key takeaways from that study.



Photo 1: Metallic inclusions in these HPHT synthetic diamonds were quick indicators of the stone’s man-made origin. Metals are rarely captured inside natural diamond as it grows in the Earth’s mantle. The presence and frequency of pieces of metal as intact inclusions in these stones indicated that what we were dealing with was of unnatural origin. In HPHT synthetic stones metal can be captured inside a crystal because the pressurized chamber (referred to as an anvil) that the diamond is forming in is made up of dense metals. Tiny bits of these metals flake off of the anvil during the procedure and are captured inside the host crystal.


Photo 2: Metallic flux was a common feature in these synthetic stones. The flux inclusions typically appear globular and rounded. While rounded crystals may occur in natural diamond the shape and relief of these inclusions was clearly inorganic. Our study found dozens of cases of metallic flux in these stones, as seen in the above examples.


Photo 3: In this photo, the metallic flux appears black and opaque where it meets the surface of the diamond.


Photo 4: Dendritic, fern-like inclusions were observed in one sample stone. Seen here at 40X and 60X, the inclusions appear fibrous and pointy. While these inclusions appear to have crystallized inside their diamond host in some pattern, the lab was not able to identify what the type of inclusion was, nor why in settled in this pattern. Destructive tests were unavailable for this study. However, given the frequency of metallic inclusions observed inside these stones it is possible that they too are of a metallic nature. That being said, they did not test as being magnetic when placed beside a strong magnet.


Photo 5: The metallic-based inclusions observed inside many of these stones meant that the vast majority of the stones were attracted to powerful magnets. While the stones themselves were not magnetized, the inclusions captured within the crystalized diamond were easily drawn to the magnet. The strength of the magnetism varied based on the quantity of metallic inclusions inside a particular stone. It is important to note that both the metallic pieces and the metallic flux were equally attracted to the magnet.



Not all of the stones that were examined in this survey exhibited the heavily included characteristics seen in the illustrations. Many sample stones were Slightly Included or even Very Slightly Included. Additionally, it is possible to create Very Very Slightly Included diamonds through the HPHT process, albeit less common than in other processes of synthesizing diamond; i.e. through the CVD process (Chemical Vapor Deposition). That being said, these visually observable features could be employed to detect a stone’s synthetic origin. While other tests like spectrum and fluorescence are also instructive, these are features that a properly trained diamond professional may observe with standard microscopic analysis.



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