Diamond Grading From A Laboratory Point Of View By Gemlab Singapore
Published: 2018-03-23   Views: 152
Author: fareastgemsjewellery17
Published in: Jewelry
Diamond Grading From A Laboratory Point Of View By Gemlab Singapore

Customer would ask these questions -

What is your procedure in testing a diamond?

When you (customer) bring in your diamond to our laboratory, the diamond is weighed using our Swiss-made Mettler Toledo. Then your diamond is measure for its dimensions using calibrated Mitutoyo Caliper. 

You already weigh my diamond, why you measure the diamond?

Diamond may have the same weight but their dimensions varies, this help dealers to make a distinction of each diamond. 

How long does you test my diamond?

About half hour to 45 min. Before proceeding to grading, we have to check whether your diamond is natural, imitations or synthetic. We used gem testing equipments like binocular microscope, prism spectroscopy, ultraviolet light, and infrared spectroscopy for this work. This is to ensure that proper identification of your diamond as synthetic and imitations are circulating in the jewellery trade. If the diamond turns out to be imitations or synthetic diamond, we would inform you and diamond will be return to you. If it is natural, then we proceed to grading it. 

Why take so long in checking?

We are careful in a diamond grading as flaw within diamond has to be scrutinized in all direction. We use Leica binocular microscope under 10x magnification to grade your diamond. Sometime a very tiny flaw as small as a pin point would affect the final grading.We cannot follow the commercial jewellery shop where they just perform the grading with just the 10x loupe. 

Further we grade the colour of your diamond with our special white light box called diamondlite and a Master diamond set graded by GIA to establish the colour of your diamond.By comparing side by side of your diamond with our known GIA diamond colour, we can establish the colour grade of your diamond. This take time. 

What is the best cut of diamond?

The diamond market has been following the quality standard of ‘hearts and arrows’since 1990s. The ‘hearts and arrows’ could be observe using an ideal-scope. Quality of the cut in diamond has to do with the proportion of a diamond i.e. crown angle and pavilion angle, and also quality of polish and symmetry. The crown angle around 34½º and pavilion angle around 40¾º will show good reflection light back to the eye of the observer. Any poorly cut diamond i.e. too deep or too shallow pavilion cut resulting in leakage of light through the back of the diamond. That is why customer sometimecomplained that their diamond does not shine. 

A well polish diamond will show a good surface reflection. Symmetry of diamond include the roundness of the diamond, any misshapen facets, misalignment of crown n pavilion also contribute to the total ‘hearts and arrows’ effect. Any misshapen facets would affect the light reflection. 

Far East Gem Lab is the first gem lab to be awarded in Singapore. Visit Gemlab.com.sg for all kind of gem valuation services. The company’s range of services includes gem identification service (gem testing), diamond grading and jewellery appraisal (jewelry appraisal). Besides the basic gemological services, the company also specialised in identification of B-jade (treated jadeite-jade – bleached and polymer impregnated), fracture-filled diamond, and some of the modern day treatment on gemstones. 


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