Professional Gem Sciences

Laboratory, Ltd.

​5 S. Wabash Avenue, Suite 315​

Chicago, IL 60603

   

© Copyright 2019  PGSL

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SERVICES

PGSL is one of the few gemological labs that promise, and deliver, uniform and consistent grading. ​Prompt service ensures that grading reports on your merchandise are issued within 24 to 96 hours of receipt. Here is a complete list of all our gemological grading reports. For price inquiries, consult the Price List page.

Quality Analysis Report

The Quality Analysis Report is a certificate attesting to the quality of a diamond. A signed document listing the results of a complete analysis including weight, color, clarity, plot, measurements, proportions, finish and fluorescence. This report will list any treatments or enhancements present in a diamond.

 

 

Above: The full Quality Analysis Report for loose diamonds.

Carte Blu

A grading report for mounted jewelry and gemstones that features a high quality image on the report. The Carte Blu consists of a complete analysis that includes weight, color, clarity, measurements and assessment of finish. At the request of the customer, this report may include an appraisal value on an article of jewelry or a finished gemstone.

Above: Carte Blu reports feature an image of the gemstone or piece of jewelry that is being examined. This report contains the results of a full gemological examination and may also have an appraisal value added to the report. 

Breakout Gemstone Sorting

PGS Lab is one of the few firms that is able to sort mass quantities of loose gemstones. The program is specifically designed for our pawnbroker clientele base. We charge per pound for the sort and then issue certificates on any good quality, valuable gemstones in the lot. 

Other

Customizable services upon request including: escrow services, expert jewelry counsel, damage reports, Sarine reports, Type IIa diamond evaluation and HPHT candidacy assessment, and much more. 

Above: For special pieces, PGSL will issue a full Jewelry Report of Quality. This is a spiral-bound report detailing a full analysis of one or many articles of jewelry. This may also include original bills of sale, auction receipts, and any additional information attesting to the provenance of jewelry. 

A Note on Standards and Terminology



Appraisals

An appraisal of a gemstone or an item of jewelry involves two operations: evaluation and valuation. Evaluation is determining the quality of the gemstone and of the mounting; valuation is then assigning a monetary value to these items, based upon their quality assessment. There are various levels and markets to consider in assigning appraisal values, depending upon the nature of the appraisal assignment. The most common type of valuation report is the insurance replacement cost appraisal. This monetary value is used primarily as the basis to determine the premium for an insurance policy on a newly acquired piece of jewelry.



Carat Weight

The carat weight of a stone is taken from a precision calibrated gemological scale. The weight is measured to the nearest thousandth and rounded up only when the digit in the thousandth column is a nine.

 

Loose Gemstone Reports

 

After identification of an unknown gemstone, we offer loose certification on that item. The report is done on a Carte Blu and offers some customizable features based on the identity of the gemstone. 

​Clarity
All clarity grades are determined using a corrected, ten-power (10X) loupe.

Color
All diamonds are color graded by two gemologists against master comparison stones. These are a set of precisely graded diamonds that are standardized for size, make and fluorescence. The color of fancy color stones are determined by comparison to Munsell color order standards, as presented in the book The World of Color.

Comments
Comments are listed if there are any features to note about that particular diamond or color stone. This will include any treatments or enhancements to the stone and may also pertain to the make and finish of a stone.

Cut Grade
Three cut grades are offered by PGSL: "Top Ideal Cut", "Ideal Cut" and "Premium Cut." Two cut designations are also provided: "Ideal Proportions" and "Premium Proportions" for stones that do not meet the very good or excellent polish grades required for a stone to receive a cut grade designation.

Plot Diagram
The plot diagram is a 2-D representation of a diamond's internal and external identifying characteristics and inclusions.