Note to The Haole Texan - once formerly known as "Stoopid Islander". The variations are normal for stained glass - by virtue of how they are frequently made. In 1955 the year before I was born, Ford decided to build the (then) world's largest float glass plant (almost 2 million sf) in Nashville. In it's day it would make about 500 tons of glass a day or about 250,000 sf. (or so I was told - but other figures would indicate they averaged much more per day). They have tight control on color, thickness, and other parameters - everything automated (have gone from something like 3000 workers now to 500 and now owned by the 6th or 7th company) Colored/stained glass manufacturers are a different entity - small batches by hand - hand transferring crucibles of molten glass to a small rolling mill from a batch oven. Each crucible slightly different by nature from the others.