Inclusions & Blemishes

Diamond Inclusions: Twinning Wisp | Rare Carat

Diamond twinning wisp shown on GIA certificate

GIA Twinning Wisp Symbol

So far, we’ve travelled all the way from bearded girdles to pinpoints. Today we shall tackle the last of our ‘internal inclusions’ (meaning those imperfections that are found inside the diamond); Twinning Wisps.

What is a Twinning Wisp?

In short, twinning wisps are veils of tiny needles, clouds, pinpoints and crystals running along the diamond's twinning plane, or caused by growth distortion. You can see their distinct wispy appearance in the diamond below.

Red arrow pointing to thin veils in round diamond called twinning wisps

In our opinion, if the diamond has a fairly high clarity grade (let’s say VS1 or above, but this is not a hard and fast rule of course) then in all likelihood that twinning wisp won't cause issues. The diamond below also has a large twinning wisp, but this diamond would probably be eye-clean.

Red arrow pointing to thin veils in round diamond called twinning wisps

Sometimes, though, twinning wisps are so dense they scatter light, making the stone look milky. Milky diamonds lose their sparkle and fire, so we steer away from dense twinning wisps, large clouds, and strong fluorescence in the colorless range. This diamond is milky from twinning wisps.

Round diamond against a black background that has turned milky from twinning wisps

If you see twinning wisp as a feature in a diamond that's VS2 or lower, make sure to get an expert opinion (ask our team of gemologists!) on whether the twinning wisps in your particular stone-of-interest will negatively affect light performance.

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Dr. Rian Mulcahy
Dr. Rian Mulcahy
Rian is officially a Diamond PhD - just ping us if you’d like to read her fascinating 200-page thesis, titled Facets of Value: An Investigation into the Formation of Worth in the Diamond Market. She has consulted various firms all along the pipeline, from the rough diamond market to the recycled diamond industry. She holds an MA in Globalisation and Development from University College Cork and a PhD in the Sociology of Diamond Valuation from the London School of Economics.