I have restoration hardware's pillows and silk curtains in silver sage. I have never regretted buying these pieces,

My Home Depot always color matches any swatch I bring in and surrounded by the beige of your wall you can't get a true color read. Surround it with white paper that usually helps.

The best quality of the three is Farrow & Ball. We've had a few clients use this produce and love the coverage and results. Beware if you're shopping price this is on the high side and worth it. Good luck

Remember, light affects colours. I am sure in the early morning, your walls..any of them...are not at all the same colour as they are after dark at night...or when you turn a lamp on. Just look at snow. The same pile of snow can be brilliant white, mauve or bluish in the morning or in shade, greyish on an overcast day, yellow at sunset. Your room with the sage walls must be facing east or north.

I have Farrow and Ball 'blackened' in my bedroom. It's a very cool slightly mauve-grey. I love it!

If F&B are too costly for you, check out this interesting article: http://laurelberninteriors.com/2015/08/02/benjamin-moore-paint-colors-matched-to-farrow-and-ball-2015/

Good luck!

Renorobin from Montreal

RH Silver Sage also showed "blue" in our home, the room gets little direct light. Tried lots of other grays, finally went with a greige, Behr Silver Tradition. Did the Rhino in the dining area, which gets a little northern light, and that looks true gray, but very dark, like wet cement. Suggest you try some greige colors, you won't get the blue, and in your light the gray should show more prominently.