They usually have red showing thru the skin at the bottom, and red streaks radiating inside--least mine did.

Carolyn says its variable in the book.

Well mine is variable on the completely yellow side! I contacted Baker Creek....no response so far.

This is probably discussed in the Baker Creeks forum idigmygarden Carolyn is often on there.

Glenda, I got a answer from Carolyn Male, and she wrote the book on heirloom tomatoes. She said she has NEVER seen a bi-colored tomato, as Big Rainbow is, that did not have the marbeling, so I dont think you have what you bought.

I got a response from Baker Creek and he wants the lot number from the seed packet which I think I still have. He also thinks I got the wrong tomato!

Thanks for you all helping me on this. The tomato is good, just not what I wanted.

I just checked and it was Pinetree! I must email Jere and apologize. It was 2008 that I ordered tomatoes from Baker Creek. Now off to contact Pinetree!