There may be some dispute among gemologists about which color and pigment shift the corundum crystal gemstone from being labeled ruby to sapphire. Rubies and sapphires are both made from corundum crystals, but rubies are generally valued higher than sapphires, according to the Gemological Institute of America (GIA).
A sapphire cannot scratch a ruby. Sapphires and rubies are both corundum, so they both have a hardness of 9.0 on the Moh Scale. Minerals that share a hardness cannot scratch one another. The only gemstone that can scratch a sapphire or ruby is a diamond. Emeralds are scratched by all three.
With hardness 9 on the Mohs scale, sapphires and rubies have long been considered virtually impervious to damage, and they can readily resist melting points even with high-karat gold solder (about 16400F to 17400F).
Rubies and pink sapphires are both from the mineral corundum, and because of this, both are given a similar 9/10 hardness rating on the Mohs scale. Ranked from 1-10, diamond is the hardest mineral, with 10 being a high score, while sapphires are just below, at 9. Because rubies and pink sapphires are both made of the mineral corundum, both are ranked only behind diamonds for hardness, at a Mohs Hardness of 9.0.
The General Durability of Rubies and Sapphires
Rubies and sapphires are very tough, and rubies are actually stronger than pink sapphires, as rubies are higher density, making it less prone to chipping or scratches. Rubies are one of the hardest minerals on Earth, ranking at 9 on the Mohs hardness scale, making them tough and resilient against scratches and wear. Garnets are composed of a darker, reddish, silicate and are far less durable than rubies, ranking between 6.5-7.5 on the Mohs scale, as opposed to rubies 9.
The only mineral harder than a ruby is a diamond, which is 10.0 out of 10.0 on the Mohs scale of mineral hardness. A ruby is second in hardness to only diamonds and Moissanite, meaning only diamonds (or objects of diamond-like hardness) can scratch it.
You can scrape the surface of the ruby with a coin, and if it leaves marks, then you probably have a fake. If you can, scratch the ruby surface with a fingernail or coin, so that the ruby does not crack.
Scratch a ruby using a number of items, using a knife, sandpaper, and a piece of glass, none of these items should scrape the ruby. If you are able to scratch your existing stones with fingernails or another sharp object, remember these are not actual stones. The only problem with this test is you cannot really tell if your stone is real or not if there is no trace of color left.
Scratchable Sapphires Are Usually Inauthentic
If your stone really scratches, even when not being brushed by a diamond or another sapphire, then that crystal is not real sapphire. Unless your crystal has been kept in an environment where it might rub against a diamond or another sapphire, your crystal is not going to get scratched. What the hardness means is that sapphire will only get scratched by a diamond, and occasionally by other sapphires, depending on each crystal’s hardness variance.
Both these statements indicate metals are scratch-free, so I cannot see how a sapphire could be scratched. Spinels are pretty tough (Mohs HardnessGiven this is a channel setting ring, and the metal above the channel is relatively un-scratched, I do have some reservations that the sapphires are actually sapphires. I cannot imagine how those stones can be scratched that badly by you, given how little wear there is on the channels.
Unlike a lot of semi-precious gems, you do not need to worry about breaking or damaging the sapphire. What this means for the sapphire is that it is a naturally durable gem, unable to scratch, break, chip, break, or suffer from any other kind of wear and tear.
Gemstones May Take on a Murkiness
Just because your ruby does not retain its color does not mean that it is not a different gem being passed off as ruby. The ruby test involves rubbing your ruby against a smooth (but firm) surface, such as glass, and seeing if the gemstone leaves color behind. You can also check your ruby at home using a high-quality jeweler’s loupe, such as this one, to find any imperfections.
If you have a natural ruby you can use as a reference, hold it along with a red-colored glass rock to a light source and look for similarities in the structures and looks. If there are any bubble-like indentations, that may be an indication the stone is glass rather than a real ruby. Natural sapphires and rubies do contain inlays, which are fissures you can see within the stone.
Sapphires contain trace amounts of iron, titanium, and nickel, giving them a variety of colors including green, yellow, blue, orange, black, and pink. Depending on the level of iron and titanium in the crystal, sapphires can come in a range of colours, though of course blue is the most well-known color for sapphires.
Sometimes Sapphires are heated with the presence of material that may seep inside the crystals and alter their color. Natural ruby and sapphire stones may also be artificially heated to have a deeper color by means of heat treatment.
Numerous Gemstone Treatments Exist
The most common is heat treating to enhance a red ruby color by removing the silk, which is a form of needle-like inclusion. Diffusion treatment is another technique that imparts color on corundum–usually a sapphire, though diffusion-treated rubies are found in smaller quantities in the marketplace.
This is because many abrasives used in jewelry making are in fact charged with corundum, and the old saying that diamonds scratch off a diamond is equally true of sapphires and rubies. It is even possible for ruby jewelry to scratch or damage other gems like emeralds or pearls, which are much less durable.
Rubies are considered to be among the most precious colored gems, often commanding higher prices per carat than sapphires and Emeralds. The intense color of Sapphires and Rubies makes them very desirable as two of the top four valuable gems, alongside Diamonds and Emeralds.