What's this weird texture under the table of lab grown diamond?

[Lyristas]

Link to the stone, a cvd lab grown 3ct marquise, vs1, E.

Image of weird texture. This is the only facet it is visible on. You only see it from specific angles in the video.

 

[musicloveranthony]

Strain - could look foggy/milky

 

[Kim N]

It's caused by growing the diamond poorly by the CVD method. There are unfortunately lots of lab diamonds out there with this effect.