The fourth precious stone is the Emerald Gemstone. It is a gemstone that is primarily in the colour green. Depending on its origins, an Emerald Gemstone may range from a lighter and darker shade of green. 

Perhaps the most interesting fact about Emerald Gemstones is that Emerald is well-known for its inclusions. While other precious stones like Diamonds, Ruby and Sapphire base their attractiveness on how little, if not no inclusions is within, Emerald is celebrated for its inclusion. 

However, this actually affects the MOHS score of the Emerald Gemstone, as it is at a lowly 7.5 to 8 as compared to Ruby and Sapphire.