The Number 5 on the pestle should corresponded to the mortar that would have the same number stamped on the bottom. When I was growing up in a small town east of New Orleans, LA, there was a French immigrant chemist who opened DeMountlazin's Drug Store. The sign out front proudly stated "established in 1900."
I remember going there as a small boy to get a Cherry Phosphate soda -- made by the immigrant's druggist son. A Cherry Phosphate was a cool drink which my mother bought for us when she took us to town. That was in the 1940s. The Drug Store had a full set of mortar and pestles ranging from extremely small to extra large vessels that resemble your No. 5 pestle. It was a pleasant sound that emitted from behind the white, marble slab counter where the original owners son formulated prescriptions by grinding different ingredients into life-saving medications. The sound was like listening to a hand-bell chiming with each clash in the brass wide-mouth mortar. I guess depending on his mood resulted in the a combination of strokes that appeared to sound like a musical rendition. So, the pestle you show is identical to one that came to this county in the early 1890s from France. Hope this didn't bore anyone, but it sure brought back some pleasant memories for me. Thanks for sharing it with us. See you at this year's convention, and I have some really good traders for you.