Wednesday, March 31, 2010

Grams & Millimeters Translated

The jewelry trade, and many others, typically measure items in millimeters, grams, and carats.  Jewelers toss these terms around as if everyone was completely comfortable with the metric system of measurements.

To help put these measurements into a context everyone understands, lets measure some common, everyday items using the metric system.  These lengths and weights are only close approximations of actual weights or lengths, but close enough to allow you to visualize what  a millimeter or a gram represents.

  •      copy paper                   measures              1/10 mm thick
  •      10 piece copy paper     measures              1 mm thick
  •      1 inch                           measures              25 mm
  •      #2 lead pencil               measures              7 mm diameter
  •      a dime                          measures              18 mm diameter
  •      USB plug                     measures               4.5 X 12 mm  W x L
  •      dollar bill                      measure                65 X 150 mm  W x L
  •      dollar bill                      weighs                  1 gram
  •      dollar bill                      weighs                  5 carats
  •      a nickle                        weighs                  5 grams


If someone throws out the term "pennyweight" instead of gram, one pennyweight (abbreviated DWT) is about 1.5 grams.  Grams are often used for weighing fabricated, or built jewelry, while pennyweight is commonly used for the weight of a cast piece.

There are five carats in one gram, and 100 points in one carat.  A 25 point diamond is 1/4 carat.