What causes sparkle in a gemstone or diamond?
By Jared James · Last updated 21 May 2026
Definition
Sparkle in a gemstone or polished metal comes from the way light bounces, bends and scatters as it interacts with the surface and interior of the piece. In diamond grading it is broken into three components: brilliance, which is the overall white light reflected back; fire, which is the splitting of light into rainbow colours; and scintillation, which is the pattern of bright and dark areas that flash as the stone or viewer moves. The cut of a diamond has the biggest influence on how much sparkle it shows.
Frequently asked questions
- What is the difference between brilliance and sparkle in a diamond?
- Brilliance is specifically the white light returned through the crown of the diamond, while sparkle is a broader term that also includes fire (coloured flashes) and scintillation (the dancing play of light and shadow as you move). A well-cut diamond shows all three.
- Does a higher carat diamond sparkle more?
- Carat refers to weight, not how much a diamond sparkles. A larger stone is more visible, so sparkle may seem more dramatic, but the actual quality of the light return depends on cut quality, not size. A smaller well-cut diamond will outshine a larger poorly-cut one.
- Which diamond shape sparkles most?
- Round brilliant cuts are engineered to return the maximum amount of light and are widely considered the sparkliest shape. Princess, oval and cushion cuts can also be very brilliant. Step cuts like emerald and Asscher have a different, more hall-of-mirrors quality rather than brilliant fire.
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