North American Gemological Laboratory evaluates jewelry, diamonds, gemstones, and time pieces for the purposes of consumer protection, estate, taxes, insurance, liquidation, probate, and inventory assessment.
NAGL Gemologists are highly trained professionals with years of education and experience. We maintain the highest standards of ethics and integrity to ensure all our clients receive accurate documentation.
The most common reason for an appraisal is insurance coverage. Diamonds, gemstones and precious metal values can fluctuate over time. It is important that appraisals be kept up-to-date to reflect current value. An accurate appraisal protects consumers in the event of loss or damage.
Many consumers are unsure which items require an appraisal. Your insurance agent can help you understand your policy requirements. Insurance guidelines vary. In general, insurance policies require an appraisal for items valued above $1,000.00. NAGL offers consultations to assist clients with determining the value of their items and whether a full appraisal is necessary. Please call to schedule a consultation.
Our staff shares the evaluation results with you and promptly answers all of your questions. The appraiser addresses any signs of damage or other concerns during the consultation. Electronic copies of the appraisal is available upon request.
We also provide mini-card appraisals for simple solitaire jewelry, loose diamonds and gemstones.
If you plan to purchase an item off the internet, contact NAGL for a verbal assessment or written appraisal. We inspect the item to verify the legitimacy of the information supplied by the merchant. We want our clients to have a clear understanding of the quality and authenticity of the item.
Make an appointment today to have your jewelry appraised or to update an old appraisal.
NAGL | North American Gemological Laboratory are experts in diamond grading. Diamond grading determines the dollar value. It is based on the “4 C’s”: color, clarity and cut (proportion), which are the quality elements, together with the carat weight determine value of a stone. Each element is based on a scale. The closer a diamond grades to the left of one or all of the scales, the rarer and more valuable the stone. Clarity is frequently assumed the most important. However, color and cut, especially cut, have the greatest affect on the appearance of a diamond.
The 4 C's
The cut of a diamond greatly determines its brilliance. A cut grade is based on a collection of measurements and observations that determine the relationship between a diamond's light performance, dimensions and finish. Most gemologists consider cut the most important diamond characteristic. High quality diamonds are cut to strict proportions. As a result, they are extremely bright and beautiful. If the cut on a high quality diamond is fair or poor than the diamond lacks brilliance.
GIA cut scale is five grades: Poor, Fair, Good, Very Good, and Excellent.
Determining a diamond's cut grade, goes beyond simple measurements of width and depth. Using a proportion analyzing device, a three-dimensional model is created to determine the diamond's proportions and angles. The relationships between the various dimensions greatly affect light’s reaction once it enters and exits the diamond. Sophisticated computer software and hardware allows light tracing to measure the levels of brightness, fire and scintillation.
Polish and symmetry are two important aspects of the cutting process. Polish grade describes the quality of the diamond's facet surface and symmetry grade refers to facet alignment. Diamonds with a poor polish are dull. Diamonds with poor symmetry leak light, which results in light rays escaping through the pavilion (lower half of the stone). Light is not reflected back to the viewer’s eye, limiting a diamond’s sparkle.
To grade the cut of a diamond, NA-GL evaluates the following:
Overall Shape or Outline
Total Depth Percentage
Grading color in the normal range involves determining how close a stone’s color approaches colorlessness. Most diamonds have a trace of yellow or brown body color, with exception of some natural fancy colors, such as blue, pink or red. The colorless grade is the most valuable. Fluorescence can impact the perceived color. To learn more about fluorescence click here.
Clarity refers to a stones relative position on a the GIA clarity scale. Clarity characteristics are classified as inclusions (internal) or blemished (external). The size, quantity, position, nature, color and relief of the characteristics determine the clarity grade. Very few diamonds are flawless, showing no inclusions or blemishes when examined by a skilled grader under 10X magnification. If other factors are equal, flawless stones are the most valuable.
The final aspect of grading a diamond is the carat. Carat is a metric unit of weight in the gem stone industry. Carat is equal to 1/5th of a gram or “5 carats in 1 gram.” The term “points” is a decimal fraction of a carat. A point is equal to .01 (1/100th) of a carat. Just as 1 dollar is equal to 100 cents, 1 carat equals 100 points.
Generally speaking, larger stones are rarer than smaller stones of the same quality. This is why the 1 carat, 20 stone cluster ring is less expensive than a 1 carat solitaire of the same quality. The size at which a gemstone increases significantly in price varies with the availability.
Carat weight and the physical size of a stone vary between species of gemstones. For example, a well cut one carat round diamond typically measures about 6.5 millimeters in diameter, but a 1 carat ruby is 5.5 to 6.0 millimeters in diameter. This is because rubies are denser and typically cut heavier than a diamond. So, a 1.5 carat stone may be needed to replace the mounting of a 1 carat diamond. Physical measurements rather than carat weight should be used to match size.
A certificate is a printed report based on results of gemological testing and analysis. Typically diamond and colored gemstone certificates are easy to read full page report prepared using an internationally recognized grading scale. A certificate will help eliminate doubts a potential buyer may have about the authenticity or quality of a particular diamond or gemstone.
The testing of a diamond or gemstone is complicated and time consuming. Our gemologists will test and analyze your diamond or colored gemstone using the latest gemological testing procedures and equipment.
When testing your diamond or gemstone we rely on education, experience, technology, and a trained eye.
Our full page diamond reports will document the following information:
Digital color photograph
Laser inscription if any
Finish details (Polish & Symmetry)
Light return analysis
Our full page colored gemstone reports will document the following information:
Digital color photograph
Stone species and variety
Hue, tone & saturation
Finish details (Polish & Symmetry)
In addition to our full certificate, we also offer our mini-card size. It is the size of a credit card and printed with the results of our testing.
In addition to jewelry appraisals we offer the following services:
Cut Grade and Light Analysis for Loose Round Diamonds. We use the latest OGI Scanox Proportion HD computer controlled proportion analyzer that will evaluate all the proportions, angles, measurements and light return of your round diamond. Once the computer completes analyzing your diamond, you received a printed report of the results. This service is especially important for recently purchased loose round diamonds from the internet. The report helps you understand the cut grade and how the proportions of your diamond determine its beauty. Please contact us for details, questions and pricing.
Report Verification. If you have an N.A.G.L. appraisal or report and need verification, please call us for confirmation of the report details.
Appraisal Updates. Appraisals should be updated every 3-5 years. Precious metals, diamonds, and gemstones fluctuate in price. To ensure current value, appraise your jewelry regularly. If jewelry is incorrectly valued you could be under or over insuring it.
Consultations. Please contact us for your specific needs.
Estate Evaluation. We appraise estate items. If you need an evaluation of an entire estate or just a few pieces, our appraisers can accurately assess estate items and prepare the proper documentation. Please contact us for details, questions and pricing.
Inventory Assessment. We evaluate entire inventories for the purchase or sale of a jewelry related business, such as a pawn shop or retail jewelry store. Please contact us for details, questions and pricing.