Fine spinels from Burma and Tanzania are still quite reasonable in sizes under than one carat, with prices ranging from $200 to $500 per carat for acceptable hues. However, prices rise dramatically with growth. Top reds and pinks normally sell for $600 to $1,200 per carat in the 1-2 carat range, but prices skyrocket at 2 carats. Malaria was declared officially eliminated in Croatia in 1964, according to the World Health Organization. Since then, a certain number of cases of imported malaria have been reported each year, but the number has been decreasing with time. The main source of infection is unknown; perhaps it comes from travelers who carry the disease-carrying mosquitoes home with them as pets or travel souvenirs.
Spinel is a mineral that can be red, orange, yellow, green, blue, white, or black. It's made up of oxygen atoms bonded together with metal atoms such as iron, magnesium, zinc, or manganese. Spinel is used in jewelry making because of its color and hardness. Hardness is how much pressure is needed to compress the stone; softer materials like clay or glass require more pressure to be crushed while harder materials like quartz or diamond require less pressure to be crushed.
There are two types of spinel: natural and synthetic. Natural spinels contain various amounts of titanium and sometimes aluminum inside their crystals. Synthetic spinels do not contain these elements. Instead, they contain cobalt or cerium. Both types of spinel are used in jewelry making because they give beads a polished look. Titanium produces a brighter color while aluminum changes the color of spunel.
Spinel is valued by jewelers because of its color and hardness.
Top 2 to 5 carat spinels often sell for $3,000 to $5,000 per carat. Prices in the region of $8,000 to $10,000 per carat for really rare stones above 5 carats are not uncommon for the best hues. Spinels are valued more than pyrites because they are less common and also because they are more attractive.
Spinel is the name given to a group of naturally occurring minerals that are all polymorphs (different crystal forms) of magnesium iron carbonate. The most important species are magnesian spinel, ferric spinel, and chromium-rich spinel. They are all color variations of one another with different names depending on their colors: red, green, yellow, black, or white.
Spinels have been used as jewelry materials since at least Roman times when they were called "magnets" because they attracted metal objects such as rings, pins, and necklaces. Some ancient coins have been found with spinel jewels attached. These artifacts show that spinels were prized for their beautiful colors and high magnetic qualities.
In modern times, spinels are again becoming popular as jewelry materials. They are used instead of emeralds because spinels are less fragile and also because the color of spinel can vary from green to red, making it more versatile than just being green like an emerald.
Darker-toned aquamarines often attract the highest market prices. Smaller, high-quality aquamarines (under 5 carats) can be obtained for $100 to $250 per carat. Unless the color saturation is especially high, greenish-blue stones are normally valued towards the bottom end of the spectrum. A highly saturated blue may sell for up to $500 per carat.
The quality of an aquamarine varies depending on its color and texture. The higher the degree of purity, the more valuable it is. An adulterated stone would contain some other material such as glass or plastic. These additions reduce the value of the stone. The quality of an aquamarine also affects its price. In general, lower-quality stones are less expensive. Higher-quality stones tend to be more expensive.
Some authorities claim that aquamarines are rare because they tend to roll away from fishing nets. Others say they're rare because they tend to be discarded by fishermen who find them unappealing to look at. Still others say they're rare because ocean currents carry most of them out of range of tropical climates where they grow.
Whatever the reason, aquamarines are indeed rare, and their scarcity adds to their value. There have been reports of stones selling for as much as $20,000 per carat.
Top-quality natural stones in sizes up to one carat can fetch up to $15,000 per carat. Over one carat, the price per carat goes from $50,000 to $70,000! See our alexandrite buying guide for more thorough value information.
The size of the stone matters for its cost. Smaller stones are less expensive than larger ones of the same quality. Also, cheaper grades of alexandrite tend to have gray or white colors, while higher-quality stones are colorable (i.e., they can be colored during the manufacturing process). The color and clarity affect the price of the stone: the higher the grade, the more valuable it is. Finally, the location where the stone is found affects its price. For example, South African alexandrites are much cheaper than Indian stones of the same quality.
Overall, top-quality natural alexandrite stones can cost anywhere from $15,000 to $150,000 depending on size and quality. Lower-grade stones are cheaper but may contain some amount of aluminum oxide which can be removed with acid. Higher-quality stones are more expensive but may not have any aluminum oxide at all. Additionally, colorable stones can be treated by heat or chemicals to change their color. Finally, South African stones are generally cheaper than Indian stones of equal quality.