Costs for creating large-sized special materials weapons?

[AGFlynn]

Has anyone seen any rules clarification for creating large size + weaons and armours out of special materials?
The half-giant in our party wants a +1 adamantine breastplate.
Now, large armour generally costs X2 of medium. Does this also apply to the extra cost of adamantine and masterworking, or is that the same as for medium armour?
Like this?:
Large Breastplate = 400 gp. + masterwork 150gp + Adamant. 10,000 g.p. + enhancement 1,000 g.p = 11,550 g.p.
Or this?:
Large Breastplate = 400 gp. + masterwork 300 g.p. (150gp x2) + Adamant. 20,000 g.p. (10,000 g.p x2) + enhancement 1,000 g.p = 21,700 g.p.
Can anyone help?
Thanks,
Flynn

 

[Ferret]

The bottom one but not doubling the masterwork bonus. The extra, special matierial is what makes it cost more. On the matirial value would (should) be doubled.