Topaz is a silicate mineral composed of aluminum and fluorine. While the stone occurs naturally in colors like colorless, yellow, and occasionally very pale blue, the vibrant blue shades seen in almost all commercial jewelry result from a permanent treatment process. This treated blue topaz is widely popular due to its brilliance and durability.
The Spectrum of Blue Topaz Shades
The blue topaz found in jewelry is categorized into three main shades based on color intensity. The lightest is Sky Blue topaz, which exhibits a delicate, pastel hue. This shade is comparable to a very pale aquamarine, often described as a soft baby blue.
Next is Swiss Blue topaz, characterized by a vibrant, electric blue color. This medium tone is bright and vivid, giving the gemstone a striking appearance. Swiss Blue is noticeably deeper than Sky Blue, making it a popular choice for pieces meant to stand out.
The darkest commercial shade is London Blue topaz, which displays a rich, deep, often grayish or inky blue. This color is the most saturated of the three, sometimes showing a subtle greenish undertone. The depth of color gives it an elegant, sophisticated appearance that rivals the look of some sapphires.
The Origin of Blue Coloration
Natural blue topaz is exceptionally rare and typically possesses a pale color, often too light to be commercially desirable. The intense, stable colors of Sky, Swiss, and London Blue are achieved by treating colorless or lightly colored natural topaz. This process involves two primary steps: irradiation followed by heating.
Irradiation exposes the topaz to a source of radiation, such as an electron accelerator, which alters the crystal lattice structure. This alteration creates “color centers,” structural defects that absorb light to produce the blue hue. Following irradiation, the topaz is subjected to heat treatment, which stabilizes the newly formed color centers.
The precise combination and duration of irradiation and heating determine the final shade of blue. Producing the deepest London Blue generally requires a higher level of radiation exposure than creating the lighter Sky Blue. The resulting blue color is permanent and will not fade under normal wear and light exposure.
Value Implications and Consumer Considerations
The rarity of naturally occurring, deeply saturated blue topaz means such a stone would command a high price, but nearly all blue topaz on the market is treated. Consequently, blue topaz is generally an affordable gemstone, making it accessible for large pieces. The price hierarchy among the treated shades usually places London Blue at the top, followed by Swiss Blue, and then Sky Blue, reflecting the intensity of the treatment required.
Consumers should be aware that the Federal Trade Commission (FTC) requires sellers to disclose that the color of blue topaz is the result of treatment. This disclosure is standard practice across the gem industry because the vast majority of stones have been enhanced. The enhancement is considered permanent and safe, but its disclosure ensures transparency in the purchase.
The affordability of treated blue topaz means that carat weight does not increase the price exponentially as it does with stones like diamonds or sapphires. A large, eye-clean blue topaz is common, as the treatment process often starts with high-clarity colorless material. Understanding that the stone’s color is scientifically enhanced allows buyers to make informed decisions based on the desired shade and size, rather than the misconception of a natural color origin.
Caring for Blue Topaz Jewelry
Topaz is a relatively hard gemstone, scoring an 8 on the Mohs scale of mineral hardness, meaning it resists scratching well during normal daily wear. However, topaz possesses a characteristic known as perfect cleavage, which is a tendency to split cleanly along certain planes when struck sharply. This structural feature means that blue topaz jewelry should be protected from hard knocks and impacts to prevent chipping or breaking.
To clean blue topaz jewelry, the safest and most effective method involves using mild dish soap and warm water. The stone can be gently scrubbed with a soft brush to remove dirt and oils that dull its brilliance. It is generally recommended to avoid using ultrasonic cleaners and steam cleaners, as the vibrations and high temperatures could potentially stress the stone or, in rare cases, affect the stability of the treated color.