worth/worthy/worthwhile

"Worth" means the value of something. 
Example: "This diamond is worth $6000 USD". 

"Worthy" means a person's worth in relation to another person, or to an honor, perhaps. 
Example: "I am not worthy of this honor". 
Example: "I am not worthy of your love". 

"Worth it" means the value of something to a particular person. 
Example: "I paid $500 for this book, and it's worth it -- worth every penny of it".

Captured from https://answers.yahoo.com/question/index?qid=20101128235929AAIp0pG

[More Useful Pages]

- https://answers.yahoo.com/question/index?qid=20101128235929AAIp0pG

- http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv271.shtml

- https://sites.google.com/site/usenglishlabsite/singihan-yeongmun/worth-worthy-jeongli

- https://answers.yahoo.com/question/index?qid=20101006080740AA1L5ZX