1 1/2 inches long, 1/2 inch wide. This looks like the pin clasp was added later because it's larger than the width of the pin. Also, there may be a dent in the top scroll part, or it could be part of the design. It has apiece of dark gray and black agate with a piece of jasper. Hallmarked "WHL with anchor, lion and lower case k.
Another shopper has this item in their Cart or Wish List.