Have you seen a Morpho butterfly with its flash of blue iridescence color? These blue flashes of color are created by an optical effect, example, interference, refraction or diffraction of light, and not by any pigment of the butterfly.
Labradorite gemstones have the Labradorescence phenomena, which is flashes of bluish light when view from certain angles. This is caused by interference of light due to the repeated twinning in Labradorite feldspar. Hence, labradorescence comes mainly from the surface of the gemstone, unlike adularescence which comes from inside the gemstone.
The bodycolor of Labradorite is usually darkish grey, though occasionally one might come across whitish grey or bluish grey. When you tilt a Labradorite rough cut gemstone, the bright flash of color against its dark grey bodycolor can be fascinating.
Labradorite is usually cut as small cabs with low dome to bring out the effect of labradorescence. Occasionally, carvings are done. A gem cutter must be careful to ensure proper orientation of the gemstone to bring out the full flash of the Labradorite gemstone.