Why emeralds are green

Up until the 20th century, leprechauns featured in literature, figurines, and art were usually dressed in red. While the tradition of wearing green on St.

As Irish immigrants made their way to America after the Great Famine of the ss, many began wearing green and carrying Irish flags along with American flags as a symbol of pride in their home country. The wearing of green became especially prominent during the annual celebration of the patron saint of Ireland, St. As Irish immigrants built upon these traditions, the practice took root in their home country as well, further emphasizing the connection of Ireland to all things green. Celebrate some St.

The Color Green Has a Strong Irish History The color green has a strong Irish history, and it is often said that the country of Ireland has over 40 shades of green present in its lush rolling hills, cliffs, and landscape countrysides. Beryl includes emerald, aquamarine, and lesser-known varieties like goshenite colorless , morganite pink , Heliodor yellow , and bixbite red. With such a drastic change in color in going from ruby to emerald resulting from a relatively small change in the ligand field, what might result from half a change in the ligand field?

The extremely rare and precious gemstone alexandrite. The absorption bands are so delicately balanced in alexandrite that in blue-rich daylight or the light from a fluorescent-tube lamp we see an intense blue-green color, resembling that of an emerald, while in red-rich candlelight or the light from an incandescent lamp we perceive a deep red color, somewhat like a ruby.

Nature has accomplished the nearly impossible task of providing a truly intermediate color between the green of emerald and the red of ruby. A synthetic alexandrite gemstone , 5 mm across, changing from a reddish color in the light from an incandescent lamp to a greenish color in the light from a fluorescent tube lamp.

One result of the symmetry of the ligand field is "pleochroism," the existence of up to three colors in different directions in a crystal. The two "dichroic" colors, orange and purple, are seen with polarized light in a ruby. The variation of the ligand field and the color in the mixed system of colorless sapphire Al 2 O 3 and chrome green Cr 2 O 3. As the chromium concentration of a ruby is increased, there is a change from red through gray to green as the ligand field becomes weaker; pure chromium oxide Cr 2 O 3 is the dark-green pigment chrome green.

A specimen on the red side of gray can be turned green by heating it to cause a reduction of the ligand field, as the atoms move apart from thermal expansion in "thermochromism"; in the reverse phenomenon "piezochromism," green can be turned red by the application of pressure. Not to scale. When small amounts of transition metals provide color in otherwise colorless substances, they are termed "allochromatic" other-colored. Examples include many gemstones, such as the chromium-based ruby, emerald, and alexandrite; the manganese-containing pink-colored morganite form of beryl; and the iron-colored blue and green aquamarines, yellow citrine, and green jade in part.

Instead, they are usually called vanadium beryl. Thus, when considering worldwide emerald value, the basic rule of thumb is no chromium, no emerald.

A vanadium emerald can be field-distinguished from a standard chromium emerald by examining it under the Chelsea Color Filter. Chromium content turns a chromium-containing emerald red when examined through the filter. The absorption spectrum is the best way to identify an emerald for certain. Chromium in beryl has known absorption lines, but vanadium has no narrow absorption lines. In fact, a vanadium emerald may broadly absorb the entire red spectrum, which removes any chance of it turning red or pink under a Chelsea Color Filter.

A few emeralds also contain dark carbon impurities inside the crystal, which can be cut to give the emerald a 6-pointed star pattern. These types of emeralds are known as trapiche emeralds, and are extremely rare outside the mines of Columbia.