The term 'Pearly White Gem' can be solved by the crossword solution 'MOONSTONE' (9 letters). Moonstones are a type of gemstone that is composed of two feldspar species, orthoclase and albite. They are known for their milky white color and shimmery appearance, which is caused by light reflecting off of the stone's layers. Moonstones are often used in jewelry and are believed to have healing properties.