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Recent News


 New Course Dates Announced for 2023

Now accepting enrollment for select classes in Spring  and Winter 2023. Register early to reserve a seat! 



This article by Tom Tashey was featured in the Summer 2009 edition of 'Gems & Gemology.' It offers some opinions on the GIA techniques for grading D to Z diamonds and encourages some critiques of methodology for the purposes of consistency in the industry. 

PGSL Seminar at National Pawnbrokers Association Annual Convention to Focus on Synthetic Diamonds


Las Vegas, NV:

Myriam Tashey spoke to a riveted crowd about the methods for detecting lab grown diamonds. This  informative program was held at the National Pawnbrokers' Association convention in Las Vegas. Her talk highlighted the market for lab-grown diamonds and the best methods for detecting them. There is much speculation and apprehension about the growing market for synthetic diamonds in our industry. Her presentation cut through the noise and presented the facts. It was also very practical, as this hands-on talk incorporated many samples of lab-grown diamonds to illustrate techniques for detection in an everyday, real world setting.

This event was the second appearance Myriam has made to the conference. Her last seminar were about gemstone enhancements. The topic was very well received and we were all thrilled to be invited back in 2019. 

This article looks at some odd laser drill techniques that were performed on a diamond which came into the laboratory recently for certification. The method detailed in the article illustrates the importance of employing great vigilance when examining any stone.

In this issue, laboratory policy to fluorescence and proper terminology are discussed at length by both PGSL and GIA lead gemologists. This issue also features a write-up on Oregon Sunstone and takes a look at Synthetic Diamonds.

In this edition, PGSL takes an in-depth look at the inclusions that are characteristic to Kashmir Sapphires. Knowing these telltale features is key to conducting origin examinations. The "Lab Notes" section takes a look at Synthetic Ruby.

​Republication of The World of Color 


After years of development, Gemworld International, in collaboration with Tom Tashey, have released this new color communication system, based on Munsell. There are over 1,600 printed colors in this master comparison book of colors. Each of 40 pages has its own unique overlay chart, developed by color scientists and adapted for use in the jewelry industry by our own team of experts.


The system comes with a colorless faceted synthetic quartz crown. When placed over a color coordinate this gives a 3-D appearance to the two dimensional colors on the charts making comparisons more effective. Cost of shipping is for two (2) books - The World of Color and its companion book explaining how to properly use the system.


Get you copy today!

PGSL Journal, Vol. 2 No. 1

This issue looks at Synthetic Moissanite and surface-enhanced topaz. A PGSL gemologist weighs in with his thoughts on laser inscribing of diamonds.

This volume explore the importance of disclosing treatment and enhancement within the jewelry industry. Another report peers into the fascinating world of chameleon diamonds, better known as color-change diamonds.

Gemstones and diamonds have a lot in common, but the clarity grading scale should not be something they share says Tom Tashey. This op-ed piece explores the usage of other laboratory terminology toward gemstones and explains why.

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