Necklace valley is a beautiful place, but you really have to want to go there! We took three days, mid-week to backpack here. One day in, one day to explore, one day out, sounds like a good idea right? The hike in is basically an easy 5 mile hike to the crossing of the East Foss river, and then 3 mile of climbing into the hanging valley where the lakes are. Only it's not really like that. The 5 miles feel easy, but as one notices on the way out, there is more up and down than you think. So... we were feeling pretty good eating lunch at the very pretty river crossing before the climb, but we were really more tired than we thought. Then we began the climb, up a pile of large scree, in and out of the forest (at least it was shady most of the hike), then up various ladders of roots, and then over ledges that required a knee up and both hands (many of these), and many nasty rocks which required careful foot-placement. There's a pretty foot-log bridge over the East Foss creek, where we saw a Pine Marten (mid-week is good for wildlife). After the creek crossing there is more rock climbing and root ladders and then more rock climbing and root ladders.. and you get the picture. When I felt like throwing up we still had half and hour of steep climb left. However we got to the valley more or less intact and camped at Iltswoot lake, the deepest and clearest lake. The next day we explored through the valley, attempting to climb to La Bonn lakes. We followed cairns up a steep slope of large scree, views were pretty good of the valley. The cairns eventually brought us to a shoulder high ledge with way too much exposure to be considered a "hike". There was no good way up and it looked like more of the same for the next hundred feet or so, so we turned around. It would have been a better idea to climb the glacial moraine up to Tank lakes, we could see the whole of it from the way to La Bonn, and it looked safe the whole way. We hiked down an meandered among the lakes, Opal is mostly a beautiful meadow, Emerald has nice camps but more mosquitos. There are a couple camps up at the head of the valley that are nice, near the start of the creek and the scree as well as camps at the lakes, some are hard to find. We did not get to check out Al, Locket or Jewel lakes, next time!
The hike down was knee and shin punishing, and the 5 miles out was very tiring after the steep descent. I would recommend doing this hike in 5 days, one to hike in to the nice camps on the river in the lower valley, then spend a day climbing the steep slope and finding a good camp at the lakes, then two days to explore, going up to tank lakes, and over to Locket and Jewel, then one day out.