Are Women Supposed To Cover Neck And Jewellery Worn There?
Chest is a private part of women. It should be covered to fulfill the command of guarding the private parts. Now how she covers it depends upon her and the culture.
Thigh is extended Awrah because it is only the private parts which are actual awrah. Zeenat is not body parts, it is something external applied on body or dress to beautify it. Old women are allowed to shake their ornaments or make up, not the body.