To find the value of a piece of carnival glass, check the size, shape and color of the base of the piece, determine whether the item belongs to the Golden Era, and look signs of damage in the piece. Compare the piece with pictures given in reference guides and auction websites.
Larger items in carnival glass pieces, such as humidors and vases, flatware, and those with unique shapes such as beads and pin holders, command a higher price than jugs and cups that are smaller and more common.
Pieces with bottoms in bright colors, as seen when held against bright light, are less expensive than those with bases in pastel shades. Red-colored pieces are rare, and hence more valuable than marigold ones, which are more common.
If the carnival glass belongs to the Golden Era, between 1920 and 1930, it normally should not have any marks, as opposed to the modern ones. Such pieces also have a satin-like finish. These pieces are considered as vintage, and hence fetch a higher value.
Presence of cracks or other signs of damage in the piece indicate that it has undergone repairs, which lowers its value. Check for the flaws using a magnifying glass. Also, if the piece has large bubbles, it is considered less valuable.
Reference guides, available online and in print form, provide information on the price of carnival glass pieces over the last few years. Auction websites provide pieces' current market prices. Generally, the price of a carnival glass piece depends on the amount a collector is ready to pay, rather than on how rare the piece is or its condition.