A window is a small polished patch ground into the crust of a rough boulder. It is the only honest look you get before the saw, and it is also the oldest trick in the trade: sellers grind the window exactly where the stone is best.
What a good buyer reads in a window is not colour. It is the way light behaves a few millimetres below the surface: whether it carries, where it stops, whether the boundary between green and grey is a hard line or a slow bleed. A hard line usually means the colour is a thin skin. A slow bleed means it goes somewhere.
The other half of the read is the crust. A sandy yellow crust often carries good colour underneath; a black crust rarely does. None of it is certain. Half the trade in Mandalay exists because none of it is certain.
Why we cut ourselves
Buying finished pieces means buying somebody else’s decisions about where the saw went. Buying rough means the mistakes are ours, which is expensive and occasionally painful, and is also the only way to know exactly what is inside the thing we sell you.