This one is embossed; Patented//Aug.26.1851. The color is peach. These have been called 'Fisher Otis' types due to the somewhat similar appearence to the rare Fisher third rail glass pin type insulators. The date shown on the body of the LRI is in reference to this patent issued to George W. Otis;

http://reference.insulators.info/patents/detail/?patent=8316&type=U

This one has an unknown history in our hobby.