See below macadam ellipse chart. This shows “True” colour of the LED in CCT – the macadam ellipses show acceptable deviation from true colour, dependent upon what has been specified:
See below representations of CIE charts of various LED fixtures. Optimal measurements should be close together on the curve, which means the optics are not changing the colour from the LED and colour shift with angle is minimal. The greater the distance, the more the colour is being changed and the further the points apart, the more the colour and CRI changes by angle.