Roman coins

[joad]

I got these in a box lot lot at an auction last week. Was wondering if anyone could tell me anything about them. I haven't removed them from the necklaces yet.

 

[Mackaydon]

They appear to be attractively mounted; why remove them from the necklace?
Top coin (two pics) appears (to these eyes) as a reproduction.
Bottom left coin represents Gordian III (238-244), Sestertius,Rome, AD 240, AE. IMP GORDIANVS PIVS FEL AVG, laureate, draped and cuirassed bust r.,
Don....
Edit: Reverse of bottom coin may be: P M TR P V COS IIP P. The coin might also represent a Denarius 'antoninianus'.