Do the idols of gods and goddesses worshipped in temples be of same colour as depicted in scriptures?
We get different rules of making idols in our scriptures:
According to Srimadbhadgavatam(11/27/12), idols can be mede of stone,wood,iron, sand, painted or covered by sindoors(लेप्या),gems and mind(मनोमयी). The Hayashirshapancharatravachana mentions the list of materials as Soil,wood,iron,gem,stone,flowers and smell( गन्धजा).The Mahakapilapancharatravachana quoted by Ragavabhatta's list of materials comprises of stone,iron,gem,wood and soil.(Reference: Shastramulak Bharatiya Shaktisadhana, Upendrakumar Das,Vol 2,page 944).
It is quite obvious that all the above materials can not be painted as per the colours mentioned in the scriptures. There is a practical side as well.Today we are used to even white idols of Sri Krishna, but earlier it was made only black.According to the dhyana manra it should be dark cloudlike blue. Gold or Silver idols are generally not coloured except drawing of eyes and lips etc. Maintaining the colours oft times is difficult as layers after layers can make the idol look blunt as it happens in many cases with layers of sindoors.
But most of the dhyanamantras of the deities describe the complexion very very clearly. For exampe, Devi Durga's dhyanamantra says Her complexion is like hot gold, Lord Krishna's dhyana says His complexion is like dark clouds, Devi Saraswati's dhyanamantra says His complexion is like Moon or Ice, Devi Radhika's dhyanamantra says Her complexion to be goldlike and so on.
By the way at least in Bengal I found very very few idols are made as per the dhyanamantra even if I dont count the colour. Not a single image of Devi Durga I have seen being worshipped during the Durga Puja that follows the various aspects of the dhyanamantra properly. I find this very unwanted..