Methodology has been developed so as to attain routine extreme conditions as high as 10-15 GPa in a gem anvil optical pressure cell using hand (manual) processed gem anvils. The anvils polished by a simplified hand held tool are inexpensive single crystal cubic zirconia (CZ) gems that have various optical advantages over diamond anvils. Appreciable pressures are attained with culet and corresponding sample cavity dimensions that are relatively convenient to load with sample material. Some technical details are provided as regards the simplified manual fabrication process, thus emphasizing the relative ease and cost effectiveness of the hand polishing technique for fabricating such high pressure anvils. Raman spectroscopy measurements, in triple subtractive mode with a confocal pinhole geometry, are used to exemplify the usefulness of the CZ gem anvil cell methodology in pressure tuning experiments. This is particularly convenient for conventional low wave-number (lattice mode regime) Raman high pressure studies, which have not been reported previously in this context. Various other applications of such anvils are suggested.