This beautiful sapphire comes from Kaduna, Nigeria. While most of the sapphires from Kaduna are deep blue or blue-green, a small number are a beautiful rich yellow, like this one. This gem has been most likely been subject to low-temperature heat treatment. The original piece of rough had a small zone of blue that I cut away to create this pure yellow finished gemstone. It has remarkable clarity, and is nearly flawless. There is some internal crystal graining and one tiny remnant of a feather visible in this macro image, they are not visible without a 10x loupe, and even then they are difficult to spot.
The sapphire weighs 2.01 carats and measures 6.9 x 5.1 mm. It would make a superb center stone for a unique engagement ring.