Please Identify Possible Ott and Brewer Mark

by Jen
(Charleston, SC)

I am a told newbie about pottery but from what I can tell, these bowls may be Ott & Brewer. However, there are no initials on the marks and every Ott & Brewer mark I saw had them. There are 10 bowls in total with varying colors and designs of the flowers. They are apx 6" in diameter.
Also, why are the bowls so dark? Almost as if they need cleaning, but it seems to be under the glaze. Is this a sign of poor quality? Or just age? Thank you so much!