The sapphire gemstone is a rare and valuable stone often used as an alternative to the diamond gemstone. With a bevy of color hues, the sapphire is an intriguing gemstone that has a rich history of value and appreciation. Ancient cultures used sapphires in alchemy and religious rituals, while prominent figures like Helen of Troy, King Solomon, and Marco Polo boasted bold, ostentatious sapphires on their person as a symbol of wealth and prosperity. What are sapphires and what should you look for when shopping for the perfect sapphire? We answer your questions and more in this article, or, if you prefer visual learning, you can watch our YouTube video below. What are Sapphires?The sapphire is a gemstone composed of corundum, an aluminum oxide mineral found in the Earth’s surface. On its own, corundum is a clear, colorless mineral as seen in the white sapphire; only when trace minerals enter the equation do sapphires gain their rainbow of hues with which we are most familiar. It is important to note that rubies are also composed of corundum, though they fall into their own gemstone category. No two sapphires will ever be completely alike; each sapphire, even within the same color family, has a wide range of hues, tones, and saturation, a different set of inclusions, and will require a slightly different cut to maximize color. Sapphires are truly unique. In addition to the diversity within this gemstone category, sapphires are highly durable, ranking only second to diamonds on the Moh’s Hardness Scale at a level 9. The Moh’s Hardness Scale, developed by Frederich Mohs in 1812, measures mineral hardness by scratching the mineral in question against another mineral that has already been measured on the scale. The result is a ranking between 1 and 10 with the diamond ranking highest on the scale and talc ranking the lowest on the scale. Corundum or sapphires are not prone to abrasions including scratches, breaking, chipping, or cracking.Image via National Parks ServiceNatural vs. Treated SapphiresCorundum requires the absence of silicon to form into the stunning gemstone we see at jewelry stores. Since silicon is a common element in the Earth’s crust, natural sapphires are rare. Furthermore, naturally, vivid-colored sapphires are even rarer causing an overwhelming majority of sapphires to undergo a heat treatment to enhance color saturation and remove unwanted colors in the stone. The heat treatment is not a new process, however, and has been a common solution to enhance sapphires for centuries. In addition to enhancing sapphire color, heat treatment can reduce inclusion size and prominence improving the clarity of the gemstone. Despite the commonality of heat treatment among corundum stones, heat treatment sapphires are priced lower than naturally colored sapphires. Heat-treated sapphires range from $1,500 to $4,500 per carat while naturally colored sapphires range from $4,000 to $15,000 per carat depending on the color, cut, clarity, and carat size of the stone. The 4Cs of SapphiresWhile the 4Cs are most commonly associated with diamond quality, sapphires are also graded by color, clarity, cut, and carat size. ColorColor is undoubtedly the most important factor when establishing the value of a sapphire gemstone. Natural corundum comes in a wide range of colors, in fact, you can find sapphires in every color of the visible spectrum. You may even encounter a sapphire with multiple colors of the spectrum in the same gemstone; hue, tone, and saturation are used to further measure the color properties of corundum.Sapphire hue refers to the sapphire gemstone’s overall color. A sapphire may have additional, secondary hues that contribute to the visual appearance of the stone i.e. a blue sapphire may have a violet secondary hue or a green secondary hue. Hue uniformity increases the value of a sapphire stone, which means that a primarily blue sapphire with minuscule secondary hues will be considered more valuable than a sapphire with a prominent secondary hue. Tone refers to the lightness or darkness of the stone. Sapphires with a medium to medium-dark tone are considered the most valuable, though this tone preference range varies slightly from color family to color family. A sapphire with a tone that is too light or too dark will impact the overall appeal of the stone. Sapphire saturation is the intensity of the stone’s color. Saturation is the most important color feature with sapphires and largely influences gemstone value. Diluted sapphires have a low saturation caused by a saturation modifier; cool-toned sapphires are diluted with grey while warm-toned sapphires are diluted with brown. Sapphires with vivid or strong saturation are considered the most valuable. Blue Sapphires7.75 Carat Oval Sapphire And Diamond Three-Stone RingBlue sapphires are the most common sapphire gemstone created by the inclusion of titanium in the corundum crystal; the higher levels of titanium in the stone, the more vivid the saturation. Blue sapphires with oversaturation can appear dark or cloudy, which decreases the value of the stone, whereas blue sapphires with weak saturation are equally undesirable. Pink SapphiresPink Sapphire Pear Shape Halo Engagement RingThe pink sapphire is both the second most popular sapphire color and the second most valuable sapphire behind the blue color variation. The pink hue of this corundum stone is created by traces of chromium in the crystal. When chromium concentration is exceptionally high, the stone becomes a ruby while a light concentration of chromium creates a romantic, pink sapphire. The pink sapphire ranges from deep pink to light purple depending on whether the trace element titanium also enters the crystal, which gives way to a more purple hue. This whimsical pink gemstone is gaining in popularity with many brides choosing the pink sapphire as their engagement ring center stone. The pink-colored corundum looks brilliant when paired with a rose gold setting, which evokes a passionately romantic feeling, especially in a pear, oval, or emerald cut. Pink Sapphire Emerald Cut Split Band Halo RingYellow Sapphires2.55 ct Oval Yellow Sapphire and Diamond RingThe yellow sapphire is an increasingly popular center stone alternative to the yellow diamond engagement ring with a rich, yellow hue that can range from greenish-yellow to orangey-yellow with varying levels of saturation. The yellow hue of the yellow sapphire is created from trace elements of iron in the corundum crystal; sometimes, titanium leaks into the crystal creating a greenish hue that is considered undesirable in a yellow sapphire gemstone. The most valuable yellow sapphire has a yellow-orange hue with a deep saturation, which pairs wonderfully with a yellow gold setting. White SapphiresEmerald-Cut White Sapphire Rose Gold Engagement RingThe white sapphire is, as we mentioned earlier, an unadulterated corundum gemstone and serves as a beautiful alternative to the diamond engagement ring. As with the diamond center stone, the white sapphire pairs nicely with all settings and metal colors, as you can see with the white sapphire engagement ring above, a rose gold setting and band create a soft appearance to the stone with a romantic flair. Green SapphiresGreen Sapphire Signature Wrap Rose Gold Engagement RingThe green sapphire is a beautiful emerald alternative with a lighter hue created by trace titanium in the corundum crystal. The green sapphire ranges from weak to vivid saturation and looks beautiful in rose gold and platinum or white gold settings. ClaritySapphire gemstones often have slight inclusions that develop during natural crystal growth. The type of inclusion in the corundum stone can affect the overall appearance of the gemstone particularly with regard to color quality. Similar to diamond clarity, when searching for the perfect sapphire, you want to find an eye-clean gemstone. VS or SI clarity grade is sufficient for a beautiful sapphire gemstone. CutWhile sapphire gemstones come in a wide variety of cuts, a great sapphire cut will achieve the following:Maximize the stone’s colorMaximize the stone’s overall carat weightMinimize the appearance of inclusions in the stone and reduce concentrations of color saturation5.46 ct Cushion Sapphire and Diamond Three-Stone RingThe best cut for a sapphire ranges from color family to color family and requires a deep look at the hues and tones of the sapphire. A well-cut sapphire will look uniform in color and will have a setting and band pairing that enhances the stone’s color palette. CaratHigh-quality natural sapphires are rarer than diamond gemstones, which dramatically increases the price of natural sapphires. Larger gemstones are particularly difficult to find, which increases the price substantially as carat size increases. There is a difference in pricing per carat between sapphire colors. Yellow sapphires, for example, are more common in larger carat sizes whereas the Padparadscha sapphire (a peachy pink-hued sapphire), which is extremely rare, is more difficult to find in larger carat sizes. Go Exotic, Choose a Sapphire GemstoneThe sapphire is exotic, has an exceptionally fun range of colors, and looks stunning as a center or accent stone. Whether you are searching for the perfect center stone for an engagement ring, entertaining the idea of adding sapphire accent stones to your three-stone ring or searching for a piece of jewelry with a pop of color, the sapphire is a wonderful gemstone with many colors from which to choose.