five-eighths inch beads?

[Ancienne Alliance]

Not sure what's shown here is large enough for you, but a Google search for "pewter beads" brought up these among other sources: http://www.artbeads.com/celtic.html

http://www.primitivearthbeads.com/pewterbeadspage1.htm

I'd also search on "beading supply" or supplies to get into the jewelry making loop -- one of my sisters does beaded necklaces, earrings etc. and there is no shortage of companies selling to that market.

Good luck!

And some larger ones here
http://www.shipwreckbeads.com/search/Celtic%20Designs

Those are great links.

Thank you for sharing.

Best,

Robert