You can eliminate Tiffin Modern. The most important aspect how to determine Tiffin Modern bi-color, ruby, emerald, smoke, sapphire, etc. on either crystal or twilight base blanks is simple. Tiffin Modern bi-color is color on crystal or color (twilight blank) on color & the color is layered on the base blank, never, ever cased...in other words the color is not encased in a crystal or colored casing, there are two distinct layers of glass, the base blank & the color layer. You can take your fingernail & easily feel where the color layer has been layered to the blank & you cannot due that with cased glass where the colors are coated with a crystal casing. There is one other U.S. company thats a bit of a fooler...Marion glass in the 50's used this same technique, usually crystal & green combinations, but examples are far from common. Ken