The vendor may substitute a color within a set due to stock issues without notice.
Due to differences in users’ monitors, the colors presented are an approximation of the true color.
PW18-Calcium Carbonate
PBk28-Black Spinel
PG7-Phthalo Green
PG17-Chromium Oxide Green
PG26-Cobalt Green Deep
PW18-Calcium Carbonate
inorganic
calcium carbonate
CaCO3
Calcium carbonate, the mineral constituent of chalk, is a low tinting strength, inexpensive white pigment that is often used is a buffer and filler. Because of its low tinting strength, it is overwhelmed by other colors. It is used in gesso and other coatings to give the surface more tooth, a desirable characteristic for some painting techniques.
Calcium carbonate is lightfast. Like all carbonates, it reacts with strong acids
Calcium carbonate is completely non-toxic, and is used in many food, cosmetic, and pharmaceutical products. However, excessive consumption is not recommended.
Naturally occuring chalk deposits have been mined since prehistoric times. Rocks and minerals that contain calcium carbonate include aragonite, calcite, vaterite, chalk, limestone. marble, and travertine. Calcium carbonate is the principle component of lime, used in many agricultural and industrial applications.
PBk28-Black Spinel
inorganic
copper chromite black
Black Spinel is a very neutral opaque black pigment, excellent for tinting to create neutral grays.
Black Spinel has excellent lightfastness.
Black Spinel is mildly toxic. The pigment itself has an extremely fine particle size. It causes irritation and ulceration to skin. Respiratory exposure and exposure to dust are serious concerns.
Black Spinel is much more expensive than carbon-based blacks. Its use as a pigment has been limited to applications where a truly neutral black or gray tone is needed.
PG7-Phthalo Green
organic
polychlorinated copper(II) phthalocyanine
C32H3Cl13CuN8 to C32HCl15CuN8 or C32H16CuN8Cl15 (PG7) or C32Br6Cl10CuN8 (PG36)
Phthalo Green is a transparent, cool, bright, high intensity color used in oil and acrylics. It comes from a Phthalocyanine Blue pigment where most of the hydrogen atoms have been replaced with chlorine, forming highly stable molecules. It has similar pigment properties and permanence to Phthalo Blue. It is slow drying and an excellent base color for mixing a range of bright greens. Phthalo Green is considered a very good alternative to Viridian because it is intense and mixes well and can be used to emphasize mineral colors in various tints. However, its tinting strength is very high, so it can overpower other colors. This pigment most closely resembles the discontinued and toxic Verdigris.
Phthalo Greens are completely lightfast and resistant to alkali, acids, solvents, heat, and ultraviolet radiation. They are currently used in inks, coatings, and many plastics due to their stability and are considered a standard pigment in printing ink and the packaging industry.
Phthalo Green has no significant hazards, but it contained PCBs (polychlorinated biphenyls) until 1982.
This bright blue-green was developed in 1935 and has been in use since 1938.
PG17-Chromium Oxide Green
inorganic
chromium oxide
Cr2O3
Chromium Oxide Green is a dull, dense, willow or pale green color that is completely opaque. It has an average drying time and a low tinting strength. It is fairly flexible in oil form and is suitable for all purposes and mediums. This pigment is less versatile in mixtures than Viridian and Phthalocyanine Green, but mixes well with other colors without overpowering them.
Chromium Oxide Green has excellent permanence, even at high temperatures.
Chromium Oxide Green is slightly toxic. Evidence of Chromium(III) carcinogenicity is inconclusive. Chromium(III) salts appear in greenish pigments such as PG17. Chromium(VI) salts, which appear in yellowish pigments, have been proven to cause cancer. 
Louis-Nicolas Vauquelin discovered the element chromium in lead chromate in 1797. It began to be used as an enamel and ceramic color in 1809, but it had limited use as a pigment until 1862, because of its cost. It is the most commonly used green for military camouflage because it appears the same shade as living foliage under infrared light.
PG26-Cobalt Green Deep
inorganic
Cobalt chromium oxide
This pigment offers a deep but dull and opaque tone of Cobalt Green. It has moderate covering power, but low tinting strength. It is primarily for use on its own, or for mixing with other cobalt colors. It is an alternative to cobalt(II) zinc oxide, another form of Cobalt Green.
Cobalt pigments are absolutely lightfast.
Cobalt chromium oxide is slightly toxic, and is a possible carcinogen.
Cobalt chromium oxide is an alternative Cobalt Green to the better known cobalt zinc oxide. Both pigments were used by landscape artists before phthalocyanine-based pigments became widely available in the 20th century.