Topaz is a really strong stone that has a Mohs hardness of eight. Diamond, ruby and sapphire are the sole commonly utilised gemstones using a better hardness. Two are pink and green bicolor stones referred to as "watermelon tourmaline." Bicolor and pleochroic tourmalines are favorite stones of many jewelry designers https://www.gemsbiz.com/blog/explore/the-july-birthstone-ruby