Sapphire is the next hardest gemstone after the diamond, and it is also one of the most expensive gems. When you buy sapphire, you should know how to evaluate the quality of the stone to guarantee that you get the best quality your money can buy.
Know what tone of blue you want.
Sapphires come in blues, with the lightest being Sweden princess blue and the darkest being navy or black. The most prized color is royal blue, which is in the middle of the scale. As the most prized, however, it is also the most expensive. Camelot and commodore blues, which are one shade lighter and darker, respectively, are similar in hue but slightly more affordable.
Take the hue into consideration.
Blue sapphires can be pure blue, or they can be tinted by green or purple. By value, pure blue ranks highest with slight purple tints following shortly after. Strong purple hues and any green hue are generally considered undesirable.
Look at the transparency of the stone. Transparency is often overlooked when buying sapphires, but the more transparent a stone is, the more brilliant it will look. Transparent stones can also be expensive, though. Fully transparent and semi-transparent stones allow the most light to pass through. Translucent sapphires allow light to pass through, but obscure objects, making it a good compromise between transparency quality and budget. Semi-opaque and opaque stones allow little to no light to pass through.
Consider a fancy color sapphire.
While blue is the most common color for a sapphire, these gemstones also come in several other colors. Padparadscha sapphires, which are orange-pink, are rare and considered valuable. Pink sapphires are also popular. Colorless, yellow, and green sapphires are significantly less prized.
Pay attention to cut.
Cut doesn’t refer to the shape of the stone. Rather, it refers to the facets on a gem’s surface, which allow light and color to shine through at their best. A deep cut sapphire has better color, while shallow stones often look too big for their own weight and look lighter in tone. The cut of a sapphire is usually rated on a scale of excellent, very good, good, fair, and poor.
Expect more inclusions with blue sapphires.
A sapphire’s clarity grade refers to the number of inclusions or cracks inside a stone. The fewer cracks, the more expensive a stone will be. Look for an official rating from a gemstone association like the GIA.
VVS (slightly included), VS (slightly included), and SI1 (slightly included) stones have few inclusions, and the inclusions they have do not effect the brilliance of the stone.
SI2 stones have inclusions that are obvious under magnification but have minor effect on the stone’s brilliance.
I1, I2, and I3 have inclusions and surface blemishes that are obvious even without magnification.