Gr53- it is not often that i get to be able to cut a bi color sapphire from the umba valley parcel. this stone has a heal fracture which does not detract from the strength of the stone, & is a visual indication of its natural origin. the combination of colors is moderate blue on one end & a light intense greenish yellow flowing from the blue to the other end of the stone. at certain angles the cut produces an optical illusion which makes the other end of the stone to have a light blue shade. defiantly a stone for those with individual tastes, to create a magnificent one off piece of jewellery. evaluation certificate from gemval can be seen in the photos & comes with the stone. please feel free to check Gemvals credentials.