Navajo Silver / Turquoise Matching Bracelet and Ring

1970's Navajo Cuff Breacelet. The makers are C. Bowie (bracelet) and H. Spencer (ring). Both pieces are sterling silver and depict a blue jay. The most interesting thing is that two different artists made these turquoise treasures. I got it from my father who purchased them during his travels in the 1970's. QUESTIONS: Has anyone heard of these artists? Are they well known artisans with other works? If anyone can assess the value of the pieces I'd be interested in your opinions. Thanks.