It looks healthy to me. What is the issue with it. It looks like it has enough sun and the pearls are plump.

Water when dry although I keep mine a little moist most of the time. Once every 15 days is too little if it is warm and sunny.

Well for instance this one used to look like this. And there’s a lot of empty and dry spots on the big one

Maybe they overwatered (or underwatered) and pulled dead/sick ones off. How long were they in others care?

What you are showing in 4th pic of op, looks pretty good while much sparser than plant in pics 1, 2 & 3 if that is the same plant.

I also agree that watering every 15 days seems to be too little - I water mine much more often than that. It also matters what kind of soil plant is in, and if they took it out of that cachepot immediately after watering.

Soil in your last pic looks quite dry and peaty - but I am looking only at the pic and could be wrong. How long do you have these plants? (if I understand correctly, you have at least 2 pots?)

So I have two string of pearls. Pics 1-3 are one plant in a hanging pot and pic 4 and the pic in comment is a much smaller 4 inch pot.

The person and the plant for two months (I went home due to COVID) but she’s actually a plant person and has many thriving string of pearls so I think she clearly knows how to take care of them. But I’m mostly concerned about the string of pearls in the hanging pot. There appears to be growth at top, shriveled or dried up in the middle, and then growth at the bottom.

My room is usually around 70 F and 50% humidity according to the Dyson app I have. The lady who had it told me to water it by feeling if it’s dry or wet with my finger one inch down but I’m just super insecure about my watering abilities so I want to make sure I’m doing okay. The soil came with The plant when I bought it so not too sure on the specifics. It was dry when I first bought it though. The pics in the post are after I watered them. Should I cut off the parts that are dried up?

also how often do you usually water them?

Oh to answer your questions, I’ve had them since early March (5 months) and I always take the catchpot off and water them and let them drain in the sink for a couple of hours. Just not sure if I’m watering properly or how I can help them.

Your watering routine sounds good - I wonder if your friend did the same?

Could it be that plant was too dry for a while and that's why there are sections in the middle of the string that are dry? If these are bit longer, I would probably cut them off and re-root healthy ends. I had mine suffer from being underwatered, and ended up cutting it quite a bit (all dry strings). Soil plants come in from store is more often than not all peat, or mostly peat. That could be difficult to keep moist 'just right'. It is advised to repot newly purchased plants in (preferably) no peat mix, or one containing very little of it.

I water mine approx. 1x/5days. Or let them get rained on if there is rain.