Hi Mochicken....
A Jumbo brown varies in size , there is no set standard.
But research I've done here and on the web suggests they are at least double the regular Coturnix.
A Coturnix averages 3-5 1/2 oz. And a jumbo is 10 oz. and larger. Average being around 12, is the info I"ve gathered.
I do not have Regular Coturnix , Just the Jumbos, and a few of mine I weighed last week are around 10.2 oz.
My A & M's are just getting feathers , so too little to weigh, but they came from Quaillady, so I"m confident they will be a great size!
Quaillady said 10 oz is a good size for a Jumbo, and these are the "Mutts" I got from Craigslist, so I don't know what all is in their background as far as breeding.
The texas A & M tends to be a little smaller.
Telling you they are the same size as her Tibetans isn't much for you to go on unless you've seen them. Have you?
If your whites were a disappointment, then I'd be a little Leary of dealing with her.
Any Coturnix can be bred to be Jumbo, but it takes time and lots of selective breeding. It's possible her Tibetans are jumbo, but slim.
I would say, is all you can do is to look good at the birds and decide for yourself.
It would be nice if someone here had pics of both sized birds side by side to judge.
ETA: Ask her where her breeding stock came from. See if that gives you anything to go on.
I found a member here at BYC that is in Tucson, and breeds buttons.. So I"m thinking someone to trade with, and I find out her eggs/stock came from Quaillady!
so much for getting new bloodlines! ROFL!