A non-photochromic R.sub.2 O-B.sub.2 O.sub.3 -SiO.sub.2 glass containing a cuprous or cuprous-cadmium halide crystal phase, having a sharp spectral cutoff at about 400 nm, the glass composition consisting essentially of, in cation percent, 35-73% SiO.sub.2, 15-45% B.sub.2 O.sub.3, 0-12% Al.sub.2 O.sub.3, the Al.sub.2 O.sub.3 being less than 10% when the SiO.sub.2 is over 55%, 0-12% Li.sub.2 O, 0-20% Na.sub.2 O, 0-12% K.sub.2 O, the Li.sub.2 O+Na.sub.2 O+K.sub.2 O being 4.75-20%, 0-5% CaO+BaO+SrO, 0.125-1.0% Cu.sub.2 O, 0-1% CdO, 0-5% ZrO.sub.2, 0-0.75% SnO.sub.2, 0-1% As.sub.2 O.sub.3 and/or Sb.sub.2 O.sub.3, the glass containing 0-1.75%. Cl, 0-1.0% Br, 0.25-2.0% Cl+Br and 0-2% F by weight, and having an R-value, calculated in mole percent of 0.15-0.45, the R-value not exceeding 0.30, except as the glass composition meets at least one condition selected from the group: up to 12 cation % Li.sub.2 O, less than 10 cation % Al.sub.2 O.sub.3, at least 0.3 cation % Cu.sub.2 O and 0.50-2.0% Cl+Br.Also, a method of making the non-photochromic glass having a sharp spectral cutoff.