The diassarion was a bronze denomination worth 2 asses - assarion in Greek.
It was commonly struck by Roman Provincial mints, and was not struck to a standard weight but rather to some local standard. It was simply a coin worth 2 of the local basic coin denomination.
It was commonly struck by Roman Provincial mints, and was not struck to a standard weight but rather to some local standard. It was simply a coin worth 2 of the local basic coin denomination.

(1)
Hadrian

An
AE
Diassarion
struck 117-138 AD
in
Sparta
Obverse: laureate bust right, draped shoulder; ΑΥΤ{Ο} ΚΑΙ{СΑΡ} ΤΡΑΙ{Α} ΑΔΡΙΑΝΟС СΕΒ{ΑС}
Reverse: Dioscuri on horses right, holding spear and reins; ΛΑΚΕΔΑΙΜΟΝΙΩΝ
Diameter:
24 mm
Die Orientation: -
Weight: 9.6 g
Die Orientation: -
Weight: 9.6 g
The information with this coin from the Albert Reeves collection says that it was bought for £2 back in 1984 from S P Kitson who graded it as 'Poor'. We have nothing else to say about it except that we are asking the same price now as it was 34 years ago.
Grunauer group XXXVII, series 1-11; RPC online Volume III, 335
(2)
Volusian

An
AE
Diassarion
struck 251-253 AD
in
Isinda
Obverse: laureate, draped and cuirassed bust right from behind; AV KE Γ OVIΔ OVEΛ OVOΛOVCCANOI
Reverse: Tyche standing half left, holding rudder and cornucopia; ICINΔ_E_ΩN / AP_X·M
Diameter:
24 mm
Die Orientation: -
Weight: 9.7 g
Die Orientation: -
Weight: 9.7 g
M., archon
H. v. Aulock, Münzen und Städte Pisidiens I, 98 f., 913-923 Taf. 20 (stgl.); SNG v. Aulock 5047 (= 913); SNG Pfalz -; SNG France 1621 (= 922).