The mantle is probably the major reservoir of Earth’s water, hosted within Nominally Anhydrous Minerals (NAMs) (e.g., Bell and Rossman, 1992; Peslier et al., 2010a,b; Nestola & Smyth 2015), in the form of hydrogen bonded to the silicate’s structural oxygen. From whence cometh this water? Is the water in these minerals representative of the Earth’s primitive upper mantle or to melting events linked to crustal formation or to more recent metasomatic/re-fertilization events? Diamonds encapsulated NAMs during their formation at literally hundreds of kilometers depth within the mantle, thereby possibly shielding and preserving their pristine water contents from re-equilibrating with fluids and melts percolating through the lithospheric mantle. Here we show that the NAMs included in diamonds from six (6) locales on the Siberian Craton contain measurable and variable H2O concentrations from 2 to 34 parts per million by weight (ppmw) in olivine, 7 to 277 ppmw in clinopyroxene, and 11-17 ppmw in garnets. Our results suggest that if the inclusions were in equilibrium with the diamond-forming fluid, the water fugacity would have been unrealistically low. Instead, we consider the H2O contents of the inclusions as pristine representatives of the residual mantle prior to encapsulation, and indicative of a protogenetic origin for the inclusions. The H2O contents of NAMs in mantle xenoliths represent some later metasomatic event(s), and are not representative of most of the continental lithospheric mantle. Results from the present study also support the conclusions of Peslier et al. (2010a, 2012) and Novella et al. (2014, 2015) that the dry nature of the SCLM of a craton provides stabilization of its thickened continental roots.