diamonds

Q: My mother has a ring which is made of white gold with a diamond stone on it. Is it permissible to wear it?

(Would it also be permissible to wear a ring made up entirely of diamond?)

Q: It is written that "Women are permitted to wear silver and gold rings. They are not allowed to wear any other type of rings besides silver and gold. Apart from rings, women are allowed to wear all types of jewellery, whether gold, silver, platinum, imitation, etc."

Is it not permissible to wear diamond rings as well?

Q: A diamond was purchased from one Muslim diamond dealer by another Muslim diamond dealer without a diamond certificate based on both diamond dealers judgments. The seller offered to send the diamond for grading and agree on a price afterwards but the buyer chose to buy it based on his judgment rather then a grading. If the diamond grading came better the seller wouldn't receive any additional cash and vice versa. On a value of 18000 the diamond dealer then viewed the diamond thoroughly and stated a slight flaw in the diamond which both parties agreed to reduce the price of the diamond to 15000. The 15000 was paid in cash to the seller. The diamond was then sent in for grading which took a period of time. The diamond came out as a treated diamond and an enhanced colour which was not known by the buyer nor seller. Based on the certification, the diamond value is only one 3rd of the price paid. Therefore the dealer that bought the diamond would like a refund on the diamond. What should be done and who should take the loss?

Q: Does it come under extravagance that a woman wears ornaments of diamonds and other precious stones which cost more than gold and silver?