One of the easiest and quickest ways gem dealers and gemologists
can determine if a stone has been heat-treated is with ultraviolet
(UV) fluorescence. Now there is an affordable tool that can help
make a first determination.
The MiniMAX™ UV-5NF
is a battery-operated, 5-watt UV lamp that is powerful, portable
and extremely practical because it provides both long-wave (365nm)
and short-wave (254nm) UV in a lightweight, compact unit. It is
powered by four 1.5-volt AA alkaline batteries (not included) and
includes an AC adapter, nylon carrying strap and convenient travel
pouch.
Under
magnification, the lamp’s short-wave UV will display chalky
fluorescence in heat-treated rubies and sapphires. Although the
color of these chalky segments may be similar to the gem being tested,
they will appear lifeless or dull. Since fissures in emeralds are
often enhanced with oils and resins, many of these will fluoresce
under the lamp’s filtered long-wave UV light. Under the lamp
and magnification, the treated segments show entirely different
colors from the rest of the gem.
Under
magnification, the lamp’s short-wave UV will display chalky
fluorescence in heat-treated rubies and sapphires. Although the
color of these chalky segments may be similar to the gem being tested,
they will appear lifeless or dull. Since fissures in emeralds are
often enhanced with oils and resins, many of these will fluoresce
under the lamp’s filtered long-wave UV light. Under the lamp
and magnification, the treated segments show entirely different
colors from the rest of the gem.