I am always interested in how jewels are made. The news cutting below outlines the strategies used by the craftsmen to make sure that, with the large opal, the necklace did not twist when worn.
Thankfully, the very few photos of QEII wearing the necklace were taken from different angles and we can see that the necklace did not twist or roll.
Prince Philip also received opal cuff links from the government of South Australia. I wonder if he has ever worn them? During the royal couple's visit to Adelaide the City gave the Prince an opal paper weight.