Below is a coin from Heraclea that looks like it has a pearl-diadem rather than a laurel wreath. I believe that this is only a peculiar Heraclean way of engraving the laurel leaves. It is also easier to engrave the leaves as small as possible. RIC VII even has a footnote for #75 on page 551- “LRBC 869 records a bust with pearl diadem for Crispus. More likely a laurel wreath depicted in a way resembling a pearl diadem.†The second coin below is more typical for the laurel bust.
Constantine I
A.D. 324
19x20mm 3.9gm
CONSTAN-TINVS AVG; Laureate (resembling pearl-diadem) head.
DN CONSTANTINI MAX AVG surrounding wreath enclosing VOT XX star in three lines.
in ex. SMHA
RIC VII Heraclea 60