In most cases, one- or two-digit numbers are actually mold numbers that indicate the specific bottle mold or section in an automatic bottle machine. If numerous molds were identical, each one received its own number. Base numbers also indicate bottle styles or shapes, manufacturing dates, or factory location codes.

What is difference between crystal and cut glass?

​Most glasses have sharp cuts, while crystals are rounded, polished and they are cut in a precise manner. Remember that crystals with over 35% lead will actually sparkle. Glass usually has a thicker rim than crystal, as it is made thicker for more durability.