Brilliant and Brilliant Vintage Synthetic core, for the professional and other demaning player. Vintage type is lower tension, for old instruments with free response. The lower tension doesn't choke the instrument, and offers more tone color. 4/4 size only. Nefrit. Competitively priced synthetic core strings especially for instruments that like high bow pressure. 4/4 Only. Ametyst Synthetic core, that is less transparent, thereby coloring the tone of an instrument to a greater extent. All sizes available. Karneol. Easy playing strings with natural tendency to produce a desireable tone without unnessary effort. 4/4 Only.