I'm using Sargasso Sea in my daily driver right now. Beautiful, rich shade of blue. My favorite blue ink to date.
I was shopping for the Topaz, but couldn't find it at a reasonable (read discounted) price. Had to settle for the Sapphire.
So, I had this bottle of yellow Delta ink gathering dust on a shelf. It was useless; not suitable for highlighting and too light to write or even draw with. I found some forgotten teal procion mx fabric dye in a drawer and figured why not?
The result you can see in the photo above. Though I would not call the color appealing, the ink is surprisingly well-behaved. I think if the dye had been navy blue it might have made a decent shade of green.