iPhone 7 plus how to find original model color from serial number / IMEI/ Model number?

I sold my iPhone 7 plus Silver 128GB which was bought new from a reputed online shop in India. IMEI and all details on box matched with details on phone screen. Person who bought it from me searched online (I have no idea whether it was on Apple website / elsewhere) and even though every detail matches and is found genuine, search results showed pic of a black iPhone at top and he is worried (But color isn't mentioned anywhere is search results). Even though I am convinced I had bought a brand new phone and I never had it repaired, out of curiosity, I want to know whether any one of you guys had similar experience. Please suggest a solution to find the original color of the phone online or any other method to decode those numbers.