How to Buy a Diamond Based on Light Performance

Are you looking to buy a beautiful diamond? These days there is a lot of contradictory information out there. What exactly does a beautiful diamond look like? In truth, it all comes down to light performance. The light performance of a diamond tells you how high-quality it is compared to other precious stones. Here are some steps that you can take to ensure that your diamond gives you the most bling for your buck.


  1. Image titled Buy a Diamond Based on Light Performance Step 1
    Understand what light performance is. A diamond has many different characteristics, including color, clarity, and carat. The most important characteristic when purchasing a diamond is its light performance, which makes a diamond outshine others in every sense of the word.
  2. Image titled Buy a Diamond Based on Light Performance Step 2
    Set your budget. Everyone has a budget and it is important to understand where you are with your money. Explore your options and see what color, clarity, and carat size you will feel most comfortable buying, then proceed.
  3. Image titled Buy a Diamond Based on Light Performance Step 3
    Find a reputable store or brand that carry diamonds with light performance information. As more information about diamonds becomes available to consumers, more and more companies are addressing these issues directly. Stores are starting to provide their own stats to customers in order to help them make decisions; find a dealer or store that understands what light performance is and can explain why it is an important part of the diamond purchasing process. This will also enable you to compare diamonds from various stores more easily.
  4. Image titled Buy a Diamond Based on Light Performance Step 4
    Use visual scopes to assess the levels of light performance in a diamond. Reflector-based visual scopes are a great way to test for the cut proportions of a diamond. The Firescope, for example, clearly shows you the difference between a diamond that is poorly cut and one that is cut perfectly without any light leakage. (Keep in mind, a diamond with light leakage will not perform as well as one that does not have any light leakage.)
  5. Image titled Buy a Diamond Based on Light Performance Step 5
    Look for a verification report. Verification should come from an independent company that can verify the light performance level of a diamond. Companies such as ImaGem, GCAL and GemEx take actual measurements of light performance under different lighting conditions. Be careful of fake reports or companies that quote “light performance” without any proof of diamond testing. Always look for direct measurement reports; these give you an accurate portrayal of a diamonds performance.
  6. Image titled Buy a Diamond Based on Light Performance Step 6
    Simply examine the appearance of each diamond you consider buying. A diamond that has high light performance will look more brilliant, have more fire, and exhibit more scintillation compared to a low performance diamond. It’s easy as that. Your knowledge of light performance should lead you to the best looking diamond, and if it doesn't, keep looking.


  • Many retailers today have new cuts for their diamonds to improve its light performance. Don't get caught up thinking that a diamond with an "ideal cut" is going to be the best--sometimes stones with more facets will have a higher Light Behavior grade.
  • Educated retailers are your best source of finding a great diamond.
  • Take care of your diamond and keep it clean to show off its performance.
  • You can use the Internet as a tool for finding retailers and diamonds that have the highest light performance based on direct measurement (exact numbers of your light behavior grade).


  • Remember: if it sounds too good to be true, it probably is.
  • Be careful of light performance reports that do not use direct measurement or do not give numerical measures.
  • No one report or test can guarantee you the highest performance. You must use multiple methods of examination--reflector scopes, reports, etc.

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Categories: Jewelry and Watches