Diamonds are strong and the name comes from the Greek word “adamas,” which means “invincible”. It’s cutting resistance is 140 times greater than rubies or sapphires, which are the next hardest gemstones. Diamonds are 10 on the Moh hardness scale. Diamonds are formed at up to 300 km deep and at very high temperatures and pressure. They come towards the surface with rising magma. They come in colorless, yellow, brown, green, blue, reddish, and orange. It is used for celebrating the 10th and 60th wedding anniversaries.