What is a Pennyweight?

"Pennyweight" is a unit of weight that originates from the weight of a medieval British silver penny. Its history is intertwined with the history of coinage, commerce, and measurement in Britain. Here's a brief overview:

  1. Roman Influence: The history of weights in the British Isles begins with the Romans, who introduced the libra (pound), which was divided into 12 uncia. This duodecimal (base-12) system continued to be influential even after the Romans departed.
  2. Anglo-Saxon Period: After the Romans left, the Anglo-Saxons introduced their system of weights, which also incorporated the duodecimal system. The "penny," as a measure of weight, took its name from the "pennig," "denarius," or "penny" which was the standard silver coin of the period.
  3. Norman England: The Normans, after their conquest in 1066, further solidified the duodecimal system. It was during this time that the weight of the penny (the actual coin) became more standardized, which consequently stabilized the measure of the pennyweight.
  4. Troy Weight System: The pennyweight is a part of the troy weight system, which was historically used in the trading and weighing of gold and silver. The system was named after the Roman weight system, based on the Roman libra. In the troy system:
    • 24 grains = 1 pennyweight (abbreviated as "dwt" for "denarius weight")
    • 20 pennyweights = 1 troy ounce
    • 12 troy ounces = 1 troy pound
  5. Medieval and Renaissance Britain: As the trading of precious metals and jewels became more refined, standardized weights became crucial. Goldsmiths, silversmiths, and jewelers preferred using the troy system, and the pennyweight remained a standard unit within it.
  6. Modern Times: While most of the world has transitioned to the metric system for weighing precious metals, the pennyweight still holds relevance, especially in the jewelry industry in certain parts of the world, including the United States.
  7. Pennyweight vs. Grams: In modern times, especially with the advent and global adoption of the metric system, many jewelers and traders now use grams. However, the pennyweight is still employed by some, and for those unfamiliar, the conversion becomes important. 1 pennyweight (dwt) is approximately equal to 1.55517384 grams.

In summary, the pennyweight's history is a reflection of the development and evolution of commerce, coinage, and trade in Britain, and by extension, in those parts of the world influenced by British trade and colonization.

What Is A Pennyweight

What industries still use the "Pennyweight"?

The pennyweight (dwt) is a unit of weight traditionally used in the troy system of weights, which has been historically associated with the trading and weighing of precious metals. While many industries have transitioned to the metric system, there are still a few sectors that utilize the pennyweight:

  1. Jewelry Industry: Jewelers often use pennyweights as a unit of measure, especially in the United States. When weighing gold, silver, and gemstones, some jewelers find it more familiar or traditional to use pennyweights instead of grams.
  2. Gold and Silver Trading: Dealers and traders of gold and silver might use pennyweights, especially when dealing with older coins or artifacts that were originally measured using the troy system.
  3. Dentistry (historically): Gold has been used in dentistry for various applications, including crowns and fillings. Historically, the weight of gold in dental applications might have been measured in pennyweights, though this has largely transitioned to the metric system.
  4. Coin Collecting: Some coin collectors and numismatists, especially those dealing with older coins, might reference the weight of coins in pennyweights, especially when the original weight of the coin was defined as such.
  5. Pawn Shops: Pawnbrokers, especially those dealing with gold and silver items, might still use pennyweights as a measure, given its traditional use in valuing precious metals.
  6. Assaying: Those involved in the assaying of precious metals might still encounter the use of pennyweights, especially when referencing historical data or when working with older practices.

However, it's worth noting that even within these industries, there's a continual shift towards the metric system, and the use of pennyweight is becoming less common.


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