When selecting glass for your project, try to buy all of it at the same time. This will allow you to see how they interact with each other, and make it easier to change what you don't like, than if you pick a few colours, and then come back later and find that nothing else will match nicely with your half finished project. Also try to view the glass you are thinking of in the same light source as the finished piece will be lit up with. Don't use a light table, as they are almost always a flourescent light bulb, which give off a blue white light and will make your glass look a lot different when exposed to a regular incandescent light bulb or sunlight.
When buying glass, buy at least 15 to 25% more than you think that you will need. This is not a ploy by us to make you buy too much glass, but to save us from your grief when you come back and only need a tiny little bit more, and we don't have it and can't get more for a few more weeks, if at all. The more desperate you are and the less you require to finish will vary proportionally to how long it will take us to get more in stock, according to Murphy's Law.
Can't figure out the area of your circle or its circumference? Well, neither can Kevin, much to his father's chagrin. He keeps muttering something about BA's versus P.Eng's? And the poor state of schooling these days. Back in his day....
The area of a circle = pi(3.14) x Diameter squared, divided by 4.
The circumference of a circle = pi(3.14) x Diameter