Focusing on the lower mark : "KB above and below the crossed pick and anvil hammer" - This is the makers mark of Krider & Biddle of Philadelphia. I have found conflicting references online as to when they were in business but trusting the information on this site puts it circa 1860 - 1870.
In regard to the George Sharp, Jr marks, I have seen auction house references to him as a silversmith but suspect he may have also been a retailer. My instinct says he was likely the retailer in this case but it could be the other way around.
Apparently Sharp was in business in Danville, Kentucky from 1857 to late 1860s moving to Atlanta, Georgia in 1871. (This information came from a US auction house so I'm unsure exactly how accurate it is.) Based on these dates though, it would place the date of manufacture at 1870 - 1871.
If you wait for the amazing Cheryl I'm sure she will be able confirm or provide more accurate info.