01

What to look for

Under 10x loupe: concentrations of extremely tiny bright dots that individually are too small to resolve. Together they form a hazy zone or cloud.

02

What it means

In diamond, clouds can reduce clarity and make a stone appear milky. In Kashmir-type sapphire, fine clouds can contribute to the prized velvety appearance.

03

Expert move

Use darkfield illumination and look obliquely. A cloud in the center is usually more visible than one near the girdle.