Rubies generally look best viewed with
incandescent light or daylight (particularly around
midday). Avoid fluorescent tubes, which have virtually
no output in the red end of the spectrum, and so cause
ruby to appear grayish.
In terms of clarity, ruby tends to
be less clean than sapphire. Buyers should look for
stones which are eye-clean, i.e., with no inclusions
visible to the unaided eye. In the case of some rubies,
extremely fine silk throughout the stone can actually
enhance the value. Many rubies also display a strong
red fluorescence to daylight, and this adds measurably
to the beauty of this gem.
While a certain amount of silk is necessary to create
the star effect in star ruby, too much silk desaturates
the color, making it appear grayish. This is not desirable.
Faceted rubies (those with flat polished
faces) are found in a variety of shapes and styles.
While ovals and cushion cuts are most commonly seen,
other shapes such as emerald cuts and hearts are not
Slight premiums are levied upon round
cut rubies due to the usually higher carat weight loss
of expensive rough crystal during cutting. Conversely,
discounts are often applied to the value of both pear
and marquise cuts.
A perfectly cut ruby should exhibit
good symmetry and polish conditions: facets should be
aligned straight in relation to the gem’s girdle
and also to each other, polish condition should be good
with no visible surface pits or polishing lines.
It could be argued that cabochons are
the most common form of cut seen in ruby. Often used
to develop and display asterism in star rubies, cabochon
cuts are most regularly applied to those rubies whose
clarity is not ideal for faceting. Well-cut proportioned
cabochons with good symmetry, which are semi-transparent
with smooth un-cracked domes, are the ideal.
Large rubies of quality are far more
rare than large sapphires of equal quality. Indeed,
any untreated ruby of quality above two carats is a
rare stone; untreated rubies of fine quality above five
carats are world-class pieces.
Ruby may display asterism, the star
effect. Fine star rubies display sharp six-rayed stars
well-centered in the middle of the cabochon. All legs
of the star should be intact and smooth. Just having
a good star does not make a stone valuable. The best
pieces have sharp stars against an intense crimson body
color. Lesser stones may have sharp stars, but the body
color is too light or grayish. On occasion, 12-rayed
star sapphires are found. Inexpensive star rubies come
mainly from India.
The original locality for ruby was
most likely Sri Lanka (Ceylon), but the classic source
is the Mogok Stone Tract in upper Burma. Fine stones
have also been found in Vietnam, along the Thai/Cambodian
border, in Kenya, Tanzania, Afghanistan, Pakistan, Yunnan
(China) and most recently, Madagascar. Low-quality rubies
also come from India and North Carolina (USA).
Large rubies of high quality are the
rarest and most highly prized of all gemstones. Rarer
than diamonds or sapphires of an equal quality and size,
any high quality piece above five Carats is considered
to be extremely rare and is almost priceless.
As the Carat weight of a ruby increases,
so does its price per Carat. As large rubies are many
times rarer than smaller rubies, per carat prices increase
disproportionately - a three Carat rubyis worth many
times more than three one Carat rubies of a comparable
Prices for ruby increase in stair-like
steps when in excess of certain significant Carat weights.
For example, a 2.02 Carat ruby commands a higher per
Carat price than a 1.98 Carat ruby, despite a negligible
difference in actual size. Ruby pricing, like that of
nearly all other gems, suffers from a “non-linear-scale
Most rubies seen on the market today
have been subjected to high temperatures in an age-old
practice that is said to have originated in Sri Lanka
some 2,000 years ago.
Rubies are heated at high temperatures
to improve their clarity and to intensify their colors.
Without this practice, we would see fewer rubies on
the market today, at far higher carat prices due to
restricted and narrowed supplies. Heating rubies makes
otherwise expensive gems, more accessible and more affordable.
The proportion of unheated rubies on
the market is very small and is widely thought to be
less than 0.5%. Although no more beautiful, their rarity
makes them highly collectable and prices are set at
a premium, sometimes fetching triple the price paid
for an equivalent heated ruby. When purchasing high
quality rubies, please be aware that unheated material
is almost non-existent, as a result, always purchase
from a reliable supplier who guarantees their gemstones
or have the seller’s claim verified by a qualified