Which gemstone in its pure form is colourless and can be mistaken for a diamond ?
Topaz
Pearl is made of calcium carbonate and is usually pale white or pink in color.
Topaz is a fluorine aluminum silicate and is usually yellow, yellow-brown, honey-yellow, flax, brown, green, blue, light blue, red and pink due to various types of impurities. Pure topaz is colorless and when cut brilliantly can be mistaken for diamond.
Amethyst is violet in color.
Ruby is the red variety of the mineral corundum.