the trend for Flower and Jewel names

In the later 19^th century in England, a vogue came in for flower and jewel names particularly among the upper classes.  Gradually, it spread downward till by the 20^th century a lot of working class girls were called by flower names. I don’t think the jewel name trend went down the social scale so much.
In mid-Victorian times, the fashion had been for “old English” names. There had been a great interest in Saxon and older English history so these  names were revived.  Names like Hilda, Edith, Emma, Ethel were common among the Saxon nobility.  For men names like Hugo, Hildebrand, Edmund, Wilfred, and Alfred etc. came into popularity.  The queen called her second son Alfred after tithe “great” Alfred…
There was also an interest in medieval history and some Norman names were revived such as Guy, Roland Oliver, etc.  Tennyson’s Idylls of the King brought in the names of the Arthurian saga, mostly for men.  There was Arthur,  Lancelot, Gareth, Tristram, Geraint, and Gawain (which became Gavin).   There were a few women in the saga, but their names were rather exotic, like Guinevere, Nimue, Liones, Lynnette and Iseult.
But in the later part of the century, (I think because of increasing secularisation  of society and a desire for “modernity”), the upper classes began to go in for more unusual names.  Many of the “Souls” (an upper class “set” who enjoyed discussing intellectual matters) produced children in the later Victorian times, (1880s etc) who had romantic names such as Cynthia, Diana, and Venetia.  
Lady Cynthia Asquith, (well-known now as a diarist) and the daughter of a “Soul” (Mary, Lady Wemyss), had a sister in law, called Violet (known as Letty)…
 Violet was also the name of H. Henry Asquith’s elder daughter.  
Violet (Letty) Charteris, Cynthia Asquith's brother's wife, was born Lady Violet Manners, daughter of another “Soul” -the Duchess of Rutland. 
 Letty married Cynthia’s brother Hugo, who was killed in World War I.
 Other flower names that became popular, were Daisy, which had started as a nickname for Margaret, Lily, Marigold, May, Pansy, Primrose, Poppy, Cherry, Heather, Hazel and Flora.  Less popular but used were names like Lavender, Hyacinth, Iris, Clematis, and Clover.  In the 20^th century, flower names went on being popular and there was a search for more unusual ones.  Some of these have remained in use even today, such as Jasmine, Fern, Holly and even Honeysuckle.  Bryony seems to have come into popularity much much later, when the vogue was over.
I think that this trend came along because people wanted something “new” which hadn’t been used before.. rather than the old names that had been around for centuries, or a revival of names that had been around thousands of years ago.  
 Working class people in Victorian times had often used bible names and virtue names such as Prudence, Faith, Hope, Charity etc.  Others were Rebecca, Rachel, Ruth and the ever popular Sarah.
Now they too went in for flower names, mostly I think Lily and Rose and Daisy.. (All names you can find in Upstairs Downstairs notably!).
The jewel name trend was less popular  among the working classes; perhaps it seemed a bit too secular.  A few jewel names did become popular among working class girls, such as Beryl, Ruby, and Pearl. 
Diamond was used because of the Queen’s Diamond jubilee year.  There were  few upper class children who received the name.   Emerald had already been used as “Esmeralda”, (a name used in Victor Hugo’s Hunchback of Notre Dame).   Maud Lady Cunard, a famous socialite, adopted it as her nickname…
There are less jewel names than flower names, so perhaps the trend wore out, because it was a bit too exotic and there wasn’t much variety. But names that have been used are Amber (still popular), Coral, Beryl, Diamond, Emerald, Garnet, (used by both sexes in Victorian times) Jade, Opal, Pearl, Ruby, Sapphire (also as Sapphira- a bible name) and Topaz.