COIN DENOMINATIONS & NOTES ON FABRICATION
Last updated: 12 November 2017
Denomination size and value comparisons
The diameters listed below are the actual measurements of the coins depicted here
Left to right - Top to bottom
Aureus (gold/AU) - .75" (20 mm) dia. = 25 denarii
Denarius (silver/AR) - .75" (20 mm) dia. = 16 asses
Sestertius (bronze/AE) - 1.5" (38 mm) dia. = 4 asses
Dupondius (bronze/AE) - 1.25" (32 mm) dia. = 2 asses
As (copper/AE) - 1.125" (28 mm) dia.
Quadrans (copper/AE) - .75" (20 mm) dia. = ¼ as
Much less frequently encountered denominations were Quinarius (gold/AU) & (silver/AR) - approx. half the size and value of the Aureus and Denarius respectively, and Semis (copper) - somewhat larger than the quadrans and twice its value.
Julio-Claudian Gold & Silver coins were very pure (98%+) making them soft and subject to significant wear in everyday use.
Fabrication (minting): First, a blank (planchet) of the correct metal composition and of the right size and weight was cast. This blank was then heated to an almost plastic state and placed on a pre-cut hardened die (the coin reverse) and the pre-cut hardened upper die (the coin obverse) positioned over it and maintained in place by by a holder (supposator) using metal tongs. A worker wielding a heavy hammer (malleator) then endeavored to strike a full square blow to the upper die on the signal of the supervisor who was sometimes the die engraver (signator). If the hold was secure and the blow of the hammer precisely administered, a perfectly round coin resulted, otherwise, the coin would be out of round which could result in partial or double struck depictions and inscriptions. The labor force of the mint consisted mostly of slaves.
Contemporary counterfeit gold and silver coins were produced by using stolen mint dies to strike copper cores which were then wrapped with a thin envelope of gold or silver. Bankers and merchants would often check the integrity of precious coins via a punch mark (shown in the Aureus photo below) or a revealing scratch (shown in the Denarius photo) in the surface of the coin.
The bronze (sometimes listed as brass) used in Roman Coinage of this time was a beautiful yellow, natural alloy of copper and zinc (in the proportion of four to one), called orichalcum.
There were two main mints: Rome and Lugdunum (modern Lyon, France). Additional Colonial mints were established from time to time.
Aureus - Augustus - RIC 206 (c. AD 1) - Lugdunum
Denarius - Augustus - RIC 38b (17 BC) - Spain (Colonial)
Sestertius - Claudius - RIC 99 (AD 41-50) - Rome
Dupondius - Caius (Caligula) - RIC 56 (AD 40-41) - Rome
As - Claudius (Germanicus) - RIC 106 (AD 50) - Rome
Quadrans - Claudius - RIC 88 (Ad 42-44) - Rome