I dug out my Leslie Field book "The Queen's Jewels." She says:

"Around 1890, the Grand Duchess commissioned a Russian jeweller to make her a diamond tiara of fifteen interlaced circles, with a swinging oriental pearl suspended in each... she left the tiara in Cartier's Paris workroom for cleaning, and while this was being done they took the opportunity of making at least three copies..."

What do we think? Is Ms Field a good source? This book was published in 1987, so (obviously) before all the misinformation that has cropped up in the last 25 years online.