If the piece you are inspecting does not appear iridescent in light, then it cannot, by definition, be a piece of carnival glass.

Genuine antique carnival glass was sprayed by hand, so the base, where the worker would hold or rest the piece on a surface, often lacks the oily reflection.

You may want to compare pieces to get a more nuanced sense of the color. You can also consult one of the countless carnival glass guidebooks available for a list of colors.

If you find a piece you can’t figure out the purpose of, check a guidebook for examples of the many kinds of glassware that was used in the early 20th Century.

Other edges include the “3 and 1,” which has 3 large crimps and one small one all around, “ribbon,” with small, tightly packed ruffles, “ice cream” edges, which have smooth, flat ruffles, and “sawtooth,” which has sharper points but the same low profile as the “ice cream” edges.

There are over 3000 recognized patterns, cast from molds, but don’t feel like you have to learn them all. Bowls are likely have one on the inner bottom, whereas cups and vases will have them on the side.

There is no measure for sheen. Pieces that sell higher at auction are deemed beautiful, but the sheen cannot be described in factual terms other than “more reflective” or “less reflective,” often called “dull” or “weak” glass. The most reflective pieces are often called “electric” carnival glass.

On the other hand, if you can determine the age, you may be able to figure out who the manufacturer is, based on the manufacturers working in the decade you’ve narrowed the piece down to and the details of the piece. You can consult a list of maker’s marks in a guidebook, or at http://www. carnivalheaven. com/carnivalglass103/id76. htm.

Grooves on the bottom typically mean that the piece is from the early 1900s, making the piece more likely to be valuable. Make sure the tool mark isn’t a crack by holding the piece up to the light, which will reveal whether the mark goes all the way through the piece or not. Cracks will appear more jagged, as well.

You can find a widely-consulted list of fakes at http://www. ddoty. com/fakes. html. These lists won’t tell you for sure whether a piece is a fake or not, as not all fakes have been determined, but it will help.