The pendant portion is 2.75"(7cm) long. It hangs from a silver plated chain with a total length of 18"(45.7cm).
According to wikipedia the purple ribbon may represent the following causes:
Domestic Violence Awareness Campaign
Spirit Day and victims of homophobia
Arnold Chiari Malformation awareness
Childhood Hemiplegia and stroke awareness
Cystic Fibrosis awareness
Alzheimer's Disease awareness
Pancreatic cancer awareness
Workers' Memorial Day
March of Dimes Awareness Ribbon
Hidradenitis Suppurativa Awareness Ribbon
The final picture shows other ribbon color options, but I can also create this piece in any color combination of available thread colors listed on my policy page.