Sapphire, especially the blue variety, is one of the most popularly traded gemstones anywhere in the world. Today, we'll teach you some helpful tips and tricks to differentiating precious sapphire from some of its more common imitation counterparts. Even some less expensive natural gems are used today as imitations to trick the inexperienced buyer.
1. Check For the Presence of Gas Bubbles.
Although many people confuse mineral or crystal inclusions with gas bubbles, only synthetic gems and glass imitations will possess raw bubbles within their material. Natural sapphire can show gas bubbles, but only when they are contained within "negative crystal" inclusions, which are basically mineral-shaped holes that have liquid suspended within them, and pockets of trapped air.
2. View Your Stone's Blue Color Under Reflected Light.
Blue sapphire will only show hues of violet, blue and dark green. Many imitations like glass and synthetic alexandrite, will show you a reddish or reddish purple color when you shine light against the stone. If you see any color other than those mentioned for sapphire, it might be best to have a gemologist look at your material. Just because a stone shows the proper color though, does not automatically mean it's authentic. Ever gem identification is a step-by-step process of deduction.
3. Look For a Colorless Plane in Sideview.
Some imitations, called assembled stones, will show you their true nature when viewed from the side. Assembled stones are comprised of two or three fused sections that are usually not of the same material. A green sapphire crown is often fused with a synthetic blue sapphire pavilion to create the deceptive look of natural blue sapphire. Likewise, colorless beryl or spinel are often fused with blue cement to create triplets that can imitate precious sapphire specimens. The colorless plane on this triplet is tricky, as the entire assembled stone's color actually comes from a colored cement layer at its mid-point.
4. Look for Intersecting Needles at 60, 120 and 180 degrees.
Sapphire is a variety of the mineral known as corundum, and some specimens tend to have inclusions of rutile, which we call "silk". These can help you determine their natural origin. Be very careful though, as many other stones can also possess needle inclusions- garnet often has needles that intersect at slightly different angles to sapphire. Assembled stones can trick you with needles on a thin crown, and glass can sometimes have elongated inclusions that one might confuse with silk.
5. Watch for Nearly Perpendicular Cleavage Directions.
Examine your stone under magnification. Sapphire does not possess any cleavage directions (planes of atomic weakness), but a close visual cousin does- Kyanite. This gems species can look extremely similar to blue sapphire in color, and is often confused with it. One big difference is that kyanite possesses nearly perpendicular cleavage directions and will often have very straight "breaks" or fractures that follow this property. Do not confuse intersecting cleavage breaks with the intersecting needles found in sapphire. If you are unsure about the inclusions found within your stone, ask a gemologist to properly check it.Lastly, glass and plastic are often used to imitate sapphire, so check for heft. Sapphire is much more dense than either of those two imitation materials, so you'll feel a distinct difference bouncing it on your palm. Many glass gemstones will also have highly abraded facet edges, because the material is much softer than sapphire, and can be victimized by wear and tear quite easily.
