The correct answer is ruby.
Corundum is an aluminum oxide mineral that is found in a variety of colors, including red (ruby), blue (sapphire), and yellow (yellow sapphire). It is the
second hardest mineral on Earth, after diamond.Garnet is a group of minerals that are all silicates of calcium, magnesium, iron, or manganese. They are found in a variety of colors, including red, green, brown, and black. Garnet is a relatively hard mineral, but it is not as hard as corundum.
Pukhraj is a yellow variety of beryl, which is a mineral group that also includes emerald and aquamarine. Beryl is a relatively hard mineral, but it is not as hard as corundum.
Pearl is an organic gemstone that is formed inside an oyster or other mollusk. It is made of calcium carbonate, which is the same material that makes up limestone. Pearl is not as hard as corundum.
In conclusion, the correct answer to the question “Carbon : Diamond :: Corundum : ?” is ruby.