Siamese cat occasionally Siamese were born with "blue" (a cool grey) points, genetically a dilution of seal point; chocolate (lighter brown) points, a genetic variation of seal point; or lilac (pale warm gray) points, genetically a diluted chocolate. These colours were at first considered "inferior" seal points, and were not qualified for showing or breeding. All of these shades were eventually accepted by the breed associations, and became more common through breeding programmes specifically aimed at producing these colours. Later, outcrosses with other breeds developed Siamese-mix cats with points in other cat colours and patterns, including Red and Cream point, lynx (tabby)
Crystallographic point group known as a crystal class. There are infinitely many three-dimensional point groups. However, the crystallographic restriction of the infinite families of general point groups results in there being only 32 crystallographic point groups. These 32 point groups are one-and-the same as the 32 types of morphological (external) crystalline symmetries derived in 1830 by Johann Friedrich Christian Hessel from a consideration of observed crystal forms. The point group of a crystal, among other things, determines directional variation of the physical properties that arise from its structure, including optical properties such as whether it is birefringent, or whether it shows the Pockels