I would leave it as it is. You are unlikely to ever get an exact match between two separate products. Trying to get it to match now with coatings, sealers and even replacement tile, will only make it more obvious that it was a failed attempt to blend the two colors. Keep it with a contrast like it is and no one will ever think it was not planned that way from the start.
You can’t go wrong with that blue. It will really sparkle and pop! If we had veered away from neutral it would have been with something like this (although my Pb made it clear that he hates working with glass tile - not that he’s actually the one physically applying it [emoji849]). Our neutral waterline line is quite similar to the one you considered. Our paving is quite different to yours though, so there would be no predicting how it would turn out.
Look at that pretty badge! LOVE it! THANKS!
Love, love, love that new tile!!!!! You are going to love how it changes in the sun and shade!
I am glad you already thought about the mortar and grout color. That is SO important for this pretty tile.
Now lets sit down and have a talk about this tile going on..............this tile can be hard to do right. Do you know if there is mesh behind it or plastic over the top of it? That will impact the ease of application but also could cause different problems. Me? I would be SO helicopter on the installers it is not even funny! "Here is another bottle of water. Oh I like how straight you are making that tile." Walk away for a few then "Here is a cookie. Oh you are doing a good job lining those little tiles all up." Be there and be oh so sweet BUT keep an eye on their work. Look at the corners and edges where they meet. Bring in breakfast/lunch depending on the time of day. Do you have to? Nope BUT if they think you are there for them then they might go the extra mile and make sure it is purrfect. They might be a little upset about having to take the old tile out and put new, harder to do, tile in.
Moving on... Put a three-foot level on the spillway. Do it today. Borrow/buy one if you don't have one. That spillway should be perfectly level, both along the front edge, and the back edge. We had a build thread here where the spillway was not level, and with the pump on low, water would spill over on one end, but not the other. When confronted about it, the PB just turned up the pump (which does mask a crooked spill way). But that means it always has to be run that way: more electricity, more pH-rise, and the fact that you can't dial down the pump to have a nice ambient water feature sound without revealing the crooked waterfall.
You want that spillway to be perfectly level, so that the water will fall over it evenly from end to end at any pump speed. Now's the time to fix it if it isn't, not when the final finish and water are in the pool and spa...