Undyed light gray cashmere/mulberry silk (50/50) from World of Wool.
The colour difference is only due to natural daylight. Silver at night, gray/beige with hints of red now. I like both. I got 802 yards from the 100g of fiber, though there were some matted bits that I discarded. shouldn't be more than a few grams, though, and I don't think it makes much difference.