Reddit mentions of Dremel 4000 Rotary Tool 175 W, Rotary Multi Tool Kit with 1 Attachment 45 Accessories, Variable Speed 5000-35000 rpm for Cutting, Carving, Sanding, Drilling, Polishing, Routing, Sharpening, Grinding

Not a problem. Ok, so if it's 14K can I assume you're based in the USA? I'm in the UK so I can only speak of my personal experience here.

Photographing jewellery is really hard, don't sweat it.

Firstly, a rhodium plate does go over the whole ring but it is only a micron layer and it does wear off. It wears off with abrasion, and the bottom of a ring will wear far more quickly than any other part of the ring. You definitely do not get a uniform change in colour as the rhodium wears. If you have worn rings either side of it, that too will wear the rhodium off of the edges of the ring, revealing the base metal alloy.

As I mentioned before, if the underlying alloy is very white or grey, then as the rhodium wears off the colour change is very minor and hard to notice. This is why we use high palladium alloys for white gold: they are grey-white and technically don't need rhodium, though we still add it.

Many of your pictures are casting colours from the surroundings so it's really hard to see, but I think that your entire ring has been made from an alloy of gold that is off-white. As your ring was sized down and no metal was added (except the sizing balls), it's almost certain that if you took some abrasive to the more-white looking top half of your ring, it too would show as yellow-ish.

There is no solution to this issue short of making a whole new ring. You can do a band-aid fix, and ask a jeweller for a heavy palnick plate (palladium-nickel), but that won't last that much longer than just rhodium.

There's no guarantee that I am right here, but if I had the ring in front of me i would be able to tell you in seconds. Any independent, well reviewed jeweller can tell you what you're dealing with. Just don't go to chain shops. Ideally, you want to speak to an actual jeweller who repairs/makes things, not a sales assistant.

This is probably not what you want to hear, but understand when you by 14K gold, you are paying for an alloy that contains 58.5% gold. There is no mention of any of the remaining alloy that can have an strong effect on diluting the yellow colour. Remember, gold is yellow. White gold is just an alloy trying to mask it.

Good luck with it, and remember, this is most defintiely a first world problem!!!

edit

One idea, if you have a Dremel or a rotary tool, you can get cheap polishing attachments for metal. Using a very soft attachment and a little rouge you can polish the metal of your engagement ring. Yellow and white gold is very hard to distinguish within the same ring when it is very shiny, regardless of rhodium.

Rouge example: https://www.amazon.co.uk/Bolpol-Jewellers-Jewellery-compound-Polishing/dp/B0134A2ZE6/ref=sr_1_5?crid=3U4169SJ5JLM&keywords=jewellers+rouge&qid=1564187160&s=diy&sprefix=jewellers+rou%2Cdiy%2C149&sr=1-5

Polishing attachments (soft cotton, nothing hard that can cause damage, these spherical ones are ideal): https://www.amazon.co.uk/NIUPIKA-Polishing-Buffing-Accessories-Mandrel/dp/B07H4D4K6T/ref=sr_1_5?keywords=dremel+polishing&qid=1564187139&s=diy&sr=1-5

This Dremel with the flexshaft is ideal for fine control polishing: https://www.amazon.co.uk/Dremel-4000-Attachment-45-Accessories/dp/B0033UWLXI/ref=sr_1_5?keywords=dremel&qid=1564187307&s=diy&sr=1-5