Silk can describe a fabric, but for gemstones and particularly sapphires and rubies, silk takes on another dimension.

Silk is the gemological term used to define linear elements that may be part of the natural, internal properties of many rubies and sapphires, collectively known as corundum.

Frequently, silk is present in unheated corundum. It has one of our favorite properties. If viewed with powerful magnification, while moving the stone, the intersection of the silk "lines" running perpendicular to each other, flashes with iridescence. It is truly like magic from the earth herself.

In this spectacular natural sapphire, there are a few clues to its being unheated. First, it's color. Any natural purple sapphire cannot be heated. Heating changes the purple hues to blue. Second, purple sapphires can and often do, shift slightly in color and hue, varying upon the surrounding light.

This one moves from a gray-blue to light violet, to a deeper violet. Lastly, that flash of iridescence is also obliterated by heating. When it is present, you can be sure the gemstone is natural and comes from the earth in just this form (besides polishing).

At a regal 39 carats, this beauty is full of personality. The silk filaments are evident with the eye, and with close observation, even some of their inspection "light up". Small dark inclusions can be seen, mostly on one side near the bezel, and a few fainter ones on the other.

Overall, it is an ethereal and entrancing stone ready to be admired. Note that at 39 carats, at this price, it is only $628 per carat, not including the setting or diamonds. Most no-heat sapphires of this size go for 5-10x that price.

A frame of transitional cut diamonds envelopes the sapphire with 1.35 carats of light. Their color of J-K, and their clarity of VS2-SI2 provide a glowing aura to the sapphire itself.

In a setting of silver over 18k gold, the ring was created in the 1940s and is a look to be reckoned with.