We　present　the　first　demonstration　of　visible　emission　from　highly　doped　silica　glass　micro-ring　resonators　(MRRs)　through　a　third-harmonic　generation　(THG)　nonlinear　process.　We　obtain　green　light　conversion　efficiency　of　2.7×10−5　W−2　in　a　MRR　with　loaded　Q-factor　of　1.4×106　pumped　in　the　telecom　band.　A　thermal　nonlinear　model　is　developed　to　account　for　the　in-cavity　power　dependence　of　the　resonance　detuning.　Using　the　extracted　thermal　nonlinear　coefficients,　the　measured　TH　resonance　shift　is　calibrated　by　subtracting　the　thermal　nonlinear-induced　phase　mismatch　to　obtain　the　theoretical　threefold　wavelength　relationship　along　with　the　measured　cubic　power　relationship.　©　2020　Optical　Society　of　America　under　the　terms　of　the　OSA　Open　Access　Publishing　Agreement.