A lighting device, comprising: a first group of solid state light emitters, said first group of solid state light emitters comprising at least one first group solid state light emitter, each of said first group of solid state light emitters having an illumination which corresponds to a point on a 1976 CIE diagram which is spaced from a first group point by a distance such that delta u', v' relative to the first group point is not more than 0.015 on said 1976 CIE diagram, and having a forward voltage temperature dependence which is within 5 % of a first group forward voltage temperature dependence; at least one first group reference solid state light emitter, said first group reference solid state light emitter having an illumination which corresponds to a point on said 1976 CIE diagram which is spaced from said first group point by a distance such that delta u', v' relative to said first group point is not more than 0.015 on said 1976 CIE diagram, and having a forward voltage temperature dependence which is within 5 % of said first group forward voltage temperature dependence; a second group of solid state light emitters of different color to the first group of solid state light emitters; means for supplying current to said first group of solid state light emitters and said at least one first group reference solid state light emitter; and a first reference sensor which detects a light intensity of said first group reference solid state light emitter, the lighting device configured to adjust a current supplied to the second group of solid state light emitters when an intensity of the first group reference solid state light emitter, as detected by the first reference sensor, decreases, in order to adjust the combined color back to a desired hue. a first group of solid state light emitters, said first group of solid state light emitters comprising at least one first group solid state light emitter, each of said first group of solid state light emitters having an illumination which corresponds to a point on a 1976 CIE diagram which is spaced from a first group point by a distance such that delta u', v' relative to the first group point is not more than 0.015 on said 1976 CIE diagram, and having a forward voltage temperature dependence which is within 5 % of a first group forward voltage temperature dependence; at least one first group reference solid state light emitter, said first group reference solid state light emitter having an illumination which corresponds to a point on said 1976 CIE diagram which is spaced from said first group point by a distance such that delta u', v' relative to said first group point is not more than 0.015 on said 1976 CIE diagram, and having a forward voltage temperature dependence which is within 5 % of said first group forward voltage temperature dependence; a second group of solid state light emitters of different color to the first group of solid state light emitters; means for supplying current to said first group of solid state light emitters and said at least one first group reference solid state light emitter; and a first reference sensor which detects a light intensity of said first group reference solid state light emitter, the lighting device configured to adjust a current supplied to the second group of solid state light emitters when an intensity of the first group reference solid state light emitter, as detected by the first reference sensor, decreases, in order to adjust the combined color back to a desired hue.