Diocletian Attribution Help

Could be this one on Wildwinds:

RIC V 193
Obv: IMP DIOCLETIANVS AVG, laureate, draped bust right
Rev: IOVI CONSERVAT AVGG, Jupiter standing right, head left, holding thunderbolt and sceptre, eagle at foot left.
Rome mint.

But the example on Wildwinds has nothing in exergue though.

RIC V Part II 166 perhaps?



Rome workshop Alpha or Delta?

Many times trouble finding a coin of a ruler that appears in more than one RIC volume comes from looking in the wrong volume. Diocletian reformed the coinage and stopped making the old style antoniniani c.294-5 and RIC broke his coins between Volumes V and VI. If a radiate head coin of Diocletian has XXI in exergue, the coin is pre reform and will be found in RIC volume V. I believe this one has alpha, gamma or delta following XXI but whatever the letter is it is just the workshop number (gamma = shop 3) and will not affect the RIC number which is 166. Bobbyhelmet's coin is shop B but still an RIC 166.

There are some post reform large folles with XXI but all XXI antoninianus size coins are pre reform and will be in RIC Volume V. The post reform radiates did not contain silver and did not bear this alloy ratio mark for 20 parts copper to one part silver. The post reform (volume VI) radiate coins often have the mintmark higher up in the field rather than in exergue but will not include XXI as part of the mintmark.