Which is to say - not all rocks are created equal. ;-)
In anything, there is an ideal - the bestest of the best. Take Lapis, for instance. If you think of Lapis, you think of a rich blue stone - the colour of the heavens, with a sprinkling of pyrite stars. Anything else, even though just as pretty and just as durable, falls short of that mark.
So when assessing a stone for its quality, we look to see how close it is to that ideal. Is it an intense, rich blue? Is it consistently coloured?
When indicating grade, grade A is good. Grade AA is better. Grade AAA is really nice stuff.
Ok - here we go with the examples.
Meet AAA grade Lapis. Notice the richness of the colour - the overall consistency, and how the inclusions are a relatively minor part of it, overall.
Next up, we have some AA grade Lapis. Still a rich colour, but more speckling of inclusions.
Also AA grade. Gorgeous colour, but a lot of pyrite. But still - how gorgeous is this?
This is A grade. Colour is a little dilute, and now the inclusions are noticeable enough that they become a distinct part of the design.
Also A grade. The batch over all was labeled A grade. You could make an argument for some of the stones being AA grade, but notice the misty cloud on the stone on the left. I personally love this look, and the fact that this decreases the price of the stone - well, hey, bonus! That doesn't work out for me very often! And look at the pyrite inclusions in the bottom stone (fool's gold). Freaking awesome.
And if you are lusting after any of these in particular - shameless plug alert! - Wed, midnight at, www.beadfx.com. ;-) Cheers!