James I AR Halfcrown. Third Coinage of 1619-25, thistle mm (struck 1621-23). 

IACOBVS D : G : MAG : BRIT : FRA : ET : HIB : REX, king riding horse right, holding shield.
QVAE DEVS CONIVNXIT NEMO SEPARET, coat of arms. 

James I Halfcrown, James I, equestrian. S-2666. 
Third Coinage of 1619-25, thistle mm (struck 1621-23). 

Seaby 2666

Courtesy Ira & Larry Goldberg Auctioneers, Beverly Hills, CA. www.goldbergcoins.com
Sale 31: The Pre-Long Beach Auction May 30 - June 1, 2005, Lot 2151