Here is the absolute best solution (trust me, I've tried everything). Get some Future Floor Wax (I think now it's called Pledge with Future Shine) and tint it with food coloring. I use it for making canopies crystal clear on my models. And guys who build modern birds, tint it either yellow or green, depending on what they need
Future is an acrylic floor wax that dries rock solid and crystal clear. It can be brushed on or the crystal can de dipped. Because it has a water-like consistency, there are no brush marks and a paper towel will wick away the excess so there are no drip marks.
Pour some in a paper cup (enough to cover the crystal) and start adding drops of food coloring. Stir thourougly until you get the color you're looking for. If you can, find a way to suspend the crystal for dunking and drying, it'll make it easier. Dip in the crystal and then touch a small end to a paper towel. The towel will suck up any runny stuff so you don't end up with drip marks. Or, if you have to brush it on, do it in thin layers so you don't get runs. Don't worry about brush marks in the first few layers, subsequent layers will fill those in.
And if you're not happy with the results, a little bath in Windex (with ammonia) will clean it right up.
This explanation was actually harder than the procedure itself - it really is that easy.
-Fred