Hi! Welcome to iCraft!
I'm glad you asked this question about captions. I knew I read something about it once-upon-a-time, but I had forgotten. So... I went and edited a listing and put a caption on the third picture. The caption doesn't show. BUT - my understanding is that it does work behind the scenes for SEO (replacement engine optimization) purposes.
Here's what iCraft has said:
We use captions in replacement, image optimization and display them on the detailed image page.(source:
https://icraftgifts.com/forum/1517/just-a-few-questions-from-a-newbie-please-help/#msg9010)
Image captions could be used as alt tags, however, not many people add them, so for the main product image we use product title as an alt tag, instead of relying on captions.
For additional product images, all we have is captions, as we can't use the same alt tag on multiple images.
So adding captions, full of keywords, is beneficial to seo.(Source:
https://icraftgifts.com/forum/1147/what-are-and-quotcaptions-and-quot-for-in-our-pics/1/)
It's better to have Captions for all product photos. Just try to change language for each a bit to keep them unique.
Basic rules for Captions - unique, descriptive, full of relevant Keywords, longer better than shorter.
(Source:
https://icraftgifts.com/forum/1206/day-6-icraft-seo-bootcamp-what-happened/#msg7382)
So... my understanding is: robots (SEO bots) don't like repeat keywords or repeat captions - it's akin to spam to them and they will downgrade your page because of it. So only use captions when they are unique and relevant to a users understanding of the product.
With respect to showing different colours, you might as well make a listing for each colour. If the listing is for multiple items, of which the customer can specify the colour, then I would include one picture that shows all the colours and then perhaps this guidance will help:
https://icraftgifts.com/help/339/how-should-i-list-products-that-come-in-3-or-4-different-colors.phpIf the colours are made on request, then I would make a listing that says "Custom Colour" in within the product title somewhere. Then, in the listing, I might show the different materials it can be made from in one of the pictures. When creating (or editing) a listing, there's a section for "Custom Orders". Once you pick that, a drop down comes where you can put more information that you need to know from the customer in order to do the custom order. One of the things you can put in there is "What colour do you want" and tell them what you have available.