I've gotten watermelon tourmaline in those sizes (and smaller, and
larger) from www.multicolour.com.
Great service, professional, and fast. I've been very happy with my
purchases from them, up to and including a beautiful grey sapphire
briolette I bought from them. (I still haven't set it, because I
can't bear to part with it, just yet)
The tourmalines were a little included, but the inclusions were
pretty in that they added sparkle in the way the light hit them.
Also got a lovely indicolite tourmaline slice in a beautiful dark
blue that I still haven't set because I can't bear to part with it,
just yet. (My husband teased me about this until he fell in love
with a pietersite agate gem we bought.)
Hope this helps,
Moonshine Metal Creations
Less than a month to go- this baby's getting heavy!