Vintage solid 18k yellow gold ring. weight: 11 grams. It is set with a large 15.8mm by 11.5mm nodule spider web turquoise stone in deep blue with black matrix. This is certainly American turquoise that has attributes of Lander Blue, but could be Red Mountain, Blue Wind or Bisbee spider web. To see it set in 18k gold tells you that it is something good. 

The style of the setting with the twisted wire is very much like Native American, but I it is my opinion that this was made and set in Iran. There is a hard to read hallmark inside. Iranian jewelers do by American turquoise and have for years. 

It is a size 7 and measures 3/4" wide. Well weighted and comfortable on the hand. I acid tested It for 14k and 18k and it passed for both as it is 18k. Not marked with American metal purity.