Ok, so you've got some crystals but you're not sure if they are any good. If you have the equipment checking crystal quality isn't difficult. A quick look down the microscope can save you a wasted trip down to see us.
The first thing to look at is the shape and size of the crystal. Sometimes your sample might look crystalline to the naked eye, but through the microscope it will be fairly obvious (in most cases) whether you have a crystal or not.
A good quality crystal will generally have a nice regular shape such as a cube, needle or perhaps a more complicated polyhedron.
The size of the crystal can be anything from around 0.03mm for its shortest dimension to 0.7mm for its largest. Note that this is only a rough guideline. Depending on crystal quality and content we may be able to work with crystals slightly outwith this range. If it is bigger we can always cut the crystal but this isn't as good a solution as having a single crystal of the right size. Another thing to note is how light is transmitted through the crystal.Here are some questions to ask yourself