This is a cased art glass mug, produced by Thomas Webb, in the 19th century, circa 1870.
The interior glass is white. The exterior glass is a clear light sky blue. The outside of the mug is hand enameled with flowers, leaves and stems. The exterior blue glass has silver flakes embedded in the glass.
The handle is shell ribbed, in blue, with each ridge painted in gold trim. This handle was patented by Webb in 1867.
The mug or cup is 3” high and 4” wide with the handle.
The rim is polished flat. There is no beveling. The gold trim on the rim is worn with age.
The bottom is round clear blue glass with a gold trim band around the foot. The underside is slightly indented and smooth.
There are no chips, nicks or cracks.