Convex Rib
The item shown is the "Vase" with a Cranberry Frit edge.
It is speculation that Jefferson is the maker of this pattern
because of the Cranberry Frit edge. However Dugan made an
identical shaped vase with vertical ribs instead of swirled ribs.
The question of whether Dugan made items with Cranberry Frit
edges has been answered with the pattern "Fishnet Epergne".
So it is more likely that Convex Rib was made by Dugan. Time will tell.
Note: For a long time it's been believed that Jefferson made this vase. It's now known
that it was made by Northwood
See (Fishnet Epergne).