KEYSTONE (OMN) adam by Adams & Company (Pittsburgh-PA, Company Operated: 1861-1891), c1872 Introduced
• AKA: Magnet and Grape with Stippled Leaves
NOTE: Keystone appears in the c1872 Adams & Co. catalog.

NOTE: Sid Lethbriidge: ...goblet (aka) Magnet & Stippled Grape is documented (not attributed) to Adams & Co. as their Keystone pattern based on its appearance in a early 1870s catalog. The maker of the Magnet & Frosted Grape pattern is unknown but has been speculated as Boston & Sandwich. See the side by side comparison below that shows the differences between the two patterns.
image 1 of 2

Shape:
Contributor:

Shape: Table Sets
Contributor: Andy Eckroth

Shape: Spooners/Spills
Contributor: Ed Perva

Shape: Sugars
Contributor: Donald Robbins, Andy Eckroth

Shape: Pattern Comparison
Contributor: Sid Lethbridge

Shape: Catalogue/Ads
Contributor: Tom Bredehoft, MAGWV

Shape: Stemware
Contributor: Ed Perva, Matthew Cox

Shape: Bowls & Berry Sets
Contributor: Susan Smith

Shape: Bowls & Berry Sets
Contributor: Susan Smith - flint bowl

Shape: Finials
Contributor: Donald Robbins