This monogram design is from An Encyclopedia of Monograms, J. O'Kane, 1884. 

Monogram: BH

Accents/Accessories: Beaded attached bail; Biased tape border; Textured, mirrored background; Raised, central monogram

Size: 34 x 45 millimeters (1.34 x 1.77 inches)

Weight: 17 grams (0.60 ounces)

Sterling Silver Chain as shown: 16 inches - $25.00 or 18 inches - $35.00