Yellow Sapphire stands 9 on the hardness scale Keeping the 3rd situation after Diamond and Moissanite. When the gemstone is multiple carat then it may't have smooth edges. Generally misunderstood to get the shape with the gemstone, Lower usually refers back to the sides within the area on the gemstone. https://www.apsense.com/article/810029-some-historical-facts-about-sri-lankan-yellow-sapp.html