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T Edit 21 terms found

T
A grade in GIA’s Color Grading System…. at the beginning of the “Light Yellow” category.
Table
The large facet on the top of the diamond’s crown.Table – The flat facet on the top of the diamond. It is the largest facet on a cut diamond.Table: The flat facet on the top of the diamond. It is the largest facet on a cut diamond.
Table Percentage
The relationship of the table as compared to the average diameter of a round brilliant cut or the width of a fancy shape diamond. So, a diamond with a 60% table has a table which is 60% as wide as the diamond’s outline.
Tachymeter (or Tachometer)
A special scale printed on the outside of a chronograph, used to calculate the average speed traveled over a measured distance. Frequently used in auto racing to determine ‘lap times.’
Telemeter
A special scale printed on the outside of a chronograph, used to determine the distance of an object from the wearer by measuring how long it takes sound to travel that distance.
Thunderbird Bezel
Also called the Turn-O-Graph bezel in the U.K., thus named after the Turn-O-Graph watch where it was first introduced. The bezel is now fitted to select Rolex Datejust models.
Tone
One of 3 characteristics used to describe the appearance of color. Tone refers to the lightness or value of the lightness in a particular stone. See also Saturation and Hue.
Tonnueau Case
Barrel-shaped case, whereas the ends are squared and the sides bow out in a rounded convex shape.
Tool Watch
This concept refers to watches created for use in specific sports or professional activities.
Translucent
A quality of a gemstone transmitting light imperfectly so that one cannot see through the stone clearly. Star sapphire is an example of this quality.
Transparent
There are several ways a light travels through a stone. In a transparent stone, the light travels through stone with virtually no distortion. Transparent stones are clear and easy to see through. See also Translucent and Opaque.
Travel Clock
Also called portfolio or purse watches. This refers to early covered, folding or protected clocks, some of which were carried in women’s purses around the early 1900s.
Treated Diamond
Describes a polished diamond that has been altered to change its appearance, (e.g., by artificial coloration, that is, irradiation).
Treated stone
A stone that has been heated, dyed, irradiated, or stained in order to improve the color or the clarity. Also pertains to gems that have their cracks or fractures concealed by filling the material.
Trichroism
A property of a stone that will show three colors or shades of the same color when the stone is viewed through a dichroscope.
Trillion Cut
A faceted cut in a triangular shape with 44 facets.
Triplock
Rolex screw-down crown, which features a triple seal against water and dust. First patented on July 22, 19652, it features the Rolex crown underscored with three ‘dots.’
Tritium
Luminous material used on the hands and hour markers of a watch since the 1950s. This radioactive material was discontinued by Rolex around 1998, in favor of a safer material LumiNova. Modern watches containing Tritium will be marked “T”, “T25”, or “T<25” on the bottom of the dial. (Please Note: The radiation content is extremely small and is not a direct hazard to the wearer).
Twinlock
Rolex screw-down crown, which features a twin seal against water and dust. First patented on April 20, 1953, it features the Rolex crown underscored with a single horizontal ‘line.”
Twinning Wisp
A cloudy area produced by crystal structure distortion, usually associated with twinning planes.
Two-Tone (also 2-Tone or Tu-Tone)
Refers to a watch case featuring two different metals (e.g. stainless steel and yellow gold).