Andre Royer French Arts and Crafts Era "Coupe Moderne" Watercolor Rendering whetstone made of ground mineral compounds

made of ground mineral compounds and flux

7 7/8" tall x 4 1/4" wide (at base) x 2 1/4" deep

When I found him

1930s-40s or so I might guess and perhaps cut down from a larger piece

particularly on one side

Andre Royer French Arts and Crafts Era "Coupe Moderne" Watercolor Rendering whetstone made of ground mineral compoundsThis watercolor shows some damage along the top edge, as detailed, but I found it too striking and beautifully done to leave behind (and a matte over top could frame this super stylish "coupe moderne" a bit more tightly, cutting in from the edge of the paper about the same distance above and below.) What we know from Royer's beautifully hand lettered annotation at lower left is that the metal on the cocktail glass rendered is silver, the ball jade,