For a systematic approach to improve the white light quality of phosphor converted light-emitting diodes (LEDs) for general lighting applications it is imperative to get the sources of error for color constancy under control. In this context, it is essential to gain a deeper insight how the individual components of an LED package may contribute to color deviation. Typically, both monochromatic and phosphor converted light-emitting diodes are finally encapsulated by a pristine silicone layer in order to prevent mechanical damage of the LED packages. In this contribution we focus on the shapes of such encapsulation layers and discuss, based on an optical simulation procedure, their impact on the color temperatures of phosphor converted white LEDs as well as the ramifications of manufacturing imprecision of these shapes on the constancy and reproducibility of a desired color temperature.