Taxes and Inventory: Concur with the Accountant?

by Jeannie.
Hi,
Do you have any information on inventory methods for taxes?

I have always used the cash method which is easy for raw materials but I am confused as to my jewelry that is ready to sell here at home and in galleries.

Do you use the cost that it was to make it or the market price for sale? One accountant told me to take 1/3 of the market value.

Thanks for any help you can give me.

Jeannie