Sales. One component of your profit margin is your sales. Generally, the more coffee you sell, the higher your profit. There are a couple of things you can do to make sure your sales are as high as they can be. First, serve quality products. Second, hire a friendly staff.
Here, Annette Bening is in nerd glasses, those thick black frames that have become increasingly popular over the past 4 years (or so). You can see how her look is instantly transformed from the previous picture, just because of a change in frames. 3 of 19 Show All.
Any lens material that has a refractive index higher than glass (1.523) is considered a high index material. Today's high index plastic lenses sold in the United States range in refractive index from 1.54 to 1.74. One of the most popular high index lens materials has a refractive index of 1.67.