Dominoes are available in a wide variety of materials, sizes, and numbering schemes.
The most common domino sets are made of a durable heavy plastic, and available in a wide variety of colors.
Double-Six numbered sets are very common, but dominoes are also made in sets of Double-9, Double-12, Double-15, and Double-18.
Other popular domino games are Spinner, Mexican Train, and Chickenfoot.
As with most of games, many new versions are constantly being added, while some older games have faded into obscurity.
Nearly all heavy plastic dominoes sold in the USA are now imported.
Many people believe that their old domino sets are made of elephant ivory, but such sets are actually quite rare. Genuine ivory is not very dense, so ivory dominoes are lighter than a same-sized set of plastic dominoes. Natural ivory also has a visible grain resulting from the growth rings in the natural ivory tusk. The grain or growth rings are easily seen with a small magnifying glass.