This is an early 20c iris glass stones necklace. You can see a full description of iris glass on my web site - www.gillianhorsup.com - it was also called rainbow glass or rhinestones. I love these glass stones - which were made to imitate iris quartz from the river Rhine. Price £95 reference 2576 B129/16. I usually have a few examples of iris glass in my shop at Grays Antiques in central London.