Definição

• Diebreak.  A crack in the striking surface of a die, or, the raised line on a coin, medal or other struck piece resulting from that crack. Dies tend to break first near the rim, lettering, or steep-pitched relief – where the metal stress is the greatest – and progress along a path of greatest stress. Any piece struck from a die in this condition will show evidence of this diecrack, and when still very light it is called hairline, like the width of a hair.
             
              Cracks in dies resulted from a combination of imperfect annealing and tempering of the steel, and excess mechanical stress on the weakest parts of a die. Most cracks propagate or “grow” between weak points such as the sharp corners of lettering or high-point details of designs. Diecracks widen or lengthen with continued use of the die, exhibiting larger diebreak lines until a point required chasing to remove the raised lines. Continued use of the die beyond this point will probably cause the die to break where a diechip will break away leaving a cud or boss on the struck pieces. In England the term is more apt to be called  striking crack.
  Diecracks tended to occur with new designs from manually retouched dies as a result of the engraver attempting to produce a visually sharp design. The Morgan dollar was well known for large numbers of coins struck from cracked dies. This was likely a defect of the design as much as the rush to produce the coins. For large coins show this final stage, likely greater than for small coins. Cracks could also combine with chips to cause large pieces to fall from the central parts of a die.
  A collapsed die occurred when hardening and tempering of the die was incorrectly performed. The most commonly seen collapsed die has a central portion that has sunken lower than the peripheral areas. In this case the die was soft in the middle and harder near the edge. Pressure of use compressed the soft and hard steel at different rates. less common collapsed die occurs when the outer portion is too soft from having been over heated during tempering.
  A collapsed center die will make coins with the central portion higher than normal. A collapsed peripheral will produce coins that have the outer portion higher than normal. Usually, a sharp discontinuity can be seen between normal and collapsed portions, and in extreme cases this area will also be cracked. See also broken die, die flaw, sunken die. spalling.

  excerpted with permission from

  An Encyclopedia of Coin and Medal Technology

  For Artists, Makers, Collectors and Curators

  COMPILED AND WRITTEN BY D. WAYNE JOHNSON

  Roger W. Burdette, Editor

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