The allure of gemstones stems from the myriad colors and dazzling radiance.
These stunning colors are created over many years when a number of conditions
magically align. Gemstones have lasted the test of time as precious stones
that can be used to express your own unique identity or bestow power
to those who wear them.
In addition to the three main precious stones introduced below,
TASAKI offers a rich array of colors in a range of other color stones.
TASAKI invites you to come and find your own unique color stone.



It is said that the three key requirements of a precious stone are beauty, scarcity and durability.
A great deal of inspiration is gained from color stones from their value as birthstones, their myriad colors, radiance and unique shape and all of these elements strongly impact on design.
The variation of colors, color combinations, sizes and varying values make it possible to create a piece of jewelry that is truly unique.

4 Basic elements that determine the value of a color stone

The value of a color stone is determined based on weight, color, brilliance (radiance) and quality.

Weight (carat)

It is generally true that the heavier the stone the rarer it becomes. This is an important element of particularly valuable precious stones.


Color is the most important criteria in determining the value of a color stone.
Color is generally expressed in terms of the following three factors.

Color (hue) The color most visible when looking at the stone.
Brightness The brightness or darkness of the color.
Intensity The clarity and mix of grey and brown hues in the stone.
In general the more sought after stones are of medium brightness, (not overly bright or dark) with vivid and intense colors.

Brilliance (radiance)

The effect of cut proportions

cut proportions have a particularly large impact on the pavilion angle.

The effect of inclusions

a stone will appear cloudier when there are more inclusions.

The effect of the finish and proportions

poor finishing (polishing, symmetry) and overall shape are both factors which will result in a drop in surface diffuse reflection and brilliance.

The effect of optical properties of the stone (refraction index)

in general, a precious stone with a high refraction index with have greater brilliance.

Brilliance (radiance)


In general, whether inclusions are visible with the naked eye will impact on the value of color stones.
Whether or not a precious stone contains inclusions will depend on the variety of the stone. Color stones are affected by the process and environment in which they are formed and these give the color stones their unique properties.

Characteristics of TASAKI Color Stones

TASAKI offers a range of high-quality color stones or precious stones.
Compared to other domestic brands, TASAKI boasts a comprehensive lineup of gems, including semi-precious stones (tourmaline, aquamarine, garnet and tanzanite etc.) and rare stones, (padparadscha sapphire and paraiba tourmaline etc.) and each one is carefully inspected in order to offer only the highest quality stones.
We also offer a broad range of products, from high jewelry to products in a more affordable price range in a variety of original cuts unique to TASAKI.

Characteristics of TASAKI Color Stones

TASAKI Color Stones

TASAKI color stones come in a wide range of colors and varieties, but one thing that is shared by all of them is our commitment to color, brilliance and rarity and only carefully selected stones of the highest quality are chosen for our jewelry range.

Emeralds (major production areas) Columbia (Muzo, Chivor), Brazil, Zambia

Emeralds boast a magical green color reminiscent of the color of the deep waters of a tropical sea. Although the color can be described as green, hues can change depending on where they are sourced providing us with a range of colors to enjoy. Among these subtle variations, the warmth of color from emeralds sourced from Columbia are said to suit the Japanese.
* It is no exaggeration to say that it is the most stunning green found anywhere on earth.
* Although it is said that Columbia accounts for approximately 60% of emeralds sourced from all around the world, the poor locations of the mines and harsh climate make them difficult to mine.
* While emeralds are generally highly included, these inclusions are a result of the extreme process under which they are created, and are evidence of their passage through time and natural forming process.
* Highly transparent emeralds are extremely valuable. Stones with a dark green coloration are both rare and expensive. An emerald with fewer inclusions will also be more durable
* TASAKI uses emeralds primarily sourced from Columbia with a focus on brilliance.
* Avoid ultrasonic cleaning.


Rubies (main production area) Myanmar

The ruby is a gemstone characterized by its fiery red color akin to a mid-summer sun. It is the birthstone for the month of July and together with the emerald, is one of the more well-known color stones. Stones of two or more carats in weight are considered extremely hard to find, making them particularly rare and the quality of these stones will have a significant impact on their value.
* Of all the color stones, rubies produce the most beautiful red coloration.
* Rubies come in a range of hues, from cute pinkish hues to fiery and vivid reds to bewitching reds.
* Dark red rubies known as pigeon blood-red rubies are symbolic of the vivid red color associated with rubies and command the highest prices.


Sapphires (main production areas) Sri Lanka, Thailand, Myanmar, Madagascar

Sapphires, like rubies, are a gemstone variety of the mineral corundum. Of these, stones with a red tinge are called rubies while all the others are known as sapphires.
While blue sapphires are generally well-known, sapphires also come in a variety of other colors, including pink, yellow and green etc.
* While sapphires may not be as glitzy as a ruby, in comparison sapphires come in relatively larger sizes and possess a reserved strength, intelligence and stunning beauty.
* Sapphires have a tendency to become slightly darker as the color becomes more saturated. To be considered truly beautiful, sapphires must have a velvety color of slightly subtle tone (more subtle than a deep blue) and exhibit a strong brilliance.
* Fancy color sapphires: padparadscha, pink, yellow, golden and orange color sapphires are also popular. Fancy color sapphires from Madagascar have gained a lot of recent attention for their wide color range.


Aquamarine (main production areas) Brazil, Mozambique, Nigeria

* Aquamarine is characterized by its clean, crisp, refreshing properties and their sophistication. At TASAKI, we look for quality stones that are not overly light in color.
* Aquamarine tends to come in relatively larger stone sizes.
* One variety of aquamarine is a saturated color known as Santa Maria (Santa Maria Africana) and has gained strong popularity in recent years.


Rhodolite garnet (main production areas) Tanzania and other locations around the world

Rhodolite garnets with a purple red coloration somewhere between pink and violet, not dissimilar to a rose, (Greek: Rhodon) are the most popular and will drop in value when they are dark with a brownish hue.
* Rhodolite garnet comes alive and is most beautiful under natural sunlight.

Rhodolite garnet

Tanzanite (main production areas) only found in Tanzania

* Tanzanite is a relatively new stone discovered in 1970
* It is a stunning stone that produces a harmony of sapphire blue and purple which changes depending on the angle. While it is softer than its other blue cousin, the sapphire, prices are relatively reasonable, they come in large stones and a variety of shapes so they can be enjoyed in a range of designs.
* Tanzanite rates at 6-6.5 on the hardness scale and therefore requires a little more care when handling.


Amethyst (main production areas) Brazil, Zambia, Uruguay etc.

* Historically, the characteristic purple color found in amethyst carries connotations of nobility and intelligence and the amethyst is a popular stone in Japan where purple is a popular color.
* Like citrin and blue topaz, amethyst is relatively reasonably priced and therefore can be found with special, unique cuts and designs.
* Rose de France amethyst is a member of the amethyst family defined by a gentle and markedly light shade of purple and is a fashionable, well known gemstone.


Morganite (main production areas) Brazil, Pakistan, Mozambique, Madagascar

* Morganite is a pink or orange variety of beryl discovered in Madagascar and belongs to the same group as the emerald and aquamarine.
* It was named after the American financier, J.P. Morgan.
* It comes in stunning salmon pink and peach pink colors which perfectly match Japanese skin.
* Morganite has few inclusions and is strong making it clear with superior durability.


Green tourmaline (main production areas) Brazil, Namibia

* Of all the color stones, tourmaline has the greatest variety of colors.
* Blue tourmaline is particularly popular while stones with yellow or brown hues will drop in value.
* Color is basically an optical property and has the potential to grow darker therefore stones with lighter coloration are generally more popular.

Opal (main production areas) Australia, Mexico, Ethiopia

* Opal that shows a variable interplay of colors is called precious opal and is separated from the common opal and are a much prized stone.
* Australia produces a range of opal varieties, including black opal (Lightning Ridge), white opal (Cooper Pedy etc.) and boulder opal (Queensland).
* Mexico is known for its fire opal and water opal.
* In more recent years, opal similar in appearance to Mexico’s fire opal have been found in Ethiopia.
* Opal is a delicate stone and care needs to be taken to avoid cracks from impact and drying out. Ultrasonic cleaning should be avoided.