Methods for synthesizing polyDCPD via ROMP of low grade DCPD starting materials using Ruthenium or Osmium carbene complex catalyst. Transparent or translucent polyDCPD materials. The Ruthenium or Osmium carbene complex catalysts having the formula ##STR1## where M may be Os or Ru; R and R.sup.1 may be the same or different and may be hydrogen or a substituent group including C.sub.2 -C.sub.20 alkenyl, C.sub.2 -C.sub.20 alkynyl, C.sub.1 -C.sub.20 alkyl, aryl, C.sub.1 -C.sub.20 carboxylate, C.sub.1 -C.sub.20 alkoxy, C.sub.2 -C.sub.20 alkenyloxy, C.sub.2 -C.sub.20 alkynyloxy, aryloxy, C.sub.2 -C.sub.20 alkoxycarbonyl, C.sub.1 -C.sub.20 alkylthio, C.sub.1 -C.sub.20 alkylsulfonyl and C.sub.1 -C.sub.20 alkylsulfinyl; X and X.sup.1 may be the same or different and may be any anionic ligand; and L and L.sup.1 may be the same or different and may be neutral electron donor. The low grade DCPD starting materials containing less than about 97% by weight of DCPD monomers.