Colorless platelet and prismatic GaN crystals grown from a Na-Ga melt are characterized using room and low temperature photoluminescence (PL), reflectance, and micro-Raman scattering. The largest (similar to 3-4 mm) platelet shows a neutral donor-bound exciton (D-0,X) PL peak with a full-width at half-maximum (FWHM) of 2.2 meV at 1.7 K. Raman scattering reveals an A(1)(LO) phonon mode in this sample at 739 cm(-1), implying a free electron concentration (n) around 2-3 x 10(17) cm(-3). Smaller platelets grown in a pyrolytic BN crucible show even sharper exciton peaks, down to 0.22 meV FWHM. The stronger A(1)(LO) Raman peak lies at 733 cm(-1) in this case, virtually unshifted by plasmon interactions. This observation implies n is in the mid 10(16) cm(-3) range or below. Residual Zn acceptors are frequently observed, and two-electron transitions identify the binding energy of the residual donor species as 33.6 meV, which may be O-N. The 2.2 eV yellow PL band is generally weak or absent. The high purity and excellent optical properties may be due to gettering of donors such as O by the Na in the melt. (C) 2002 Elsevier Science B.V. All rights reserved.