Kashmir sapphire platinum engagement ring

Some information:
  Style: between Edwardian and Art Deco
  Style specifics: As for its elegant design, this jewel has the finesse of an Edwardian piece reacting gracefully against the very geometrical forms of Art Deco that was strongly influenced by Cubism. However, because both Edwardian and Art Deco styles were contemporaries of each other, we sometimes notice pieces - like this one - that carry both influences.
  Material: platinum.
  Diamonds: Eight old mine brilliant cut diamonds with a total estimated weight of approx. 0.16 crt. Note: All diamond weights, color grades and clarity are approximate since the stones were not removed from their mounts to preserve the integrity of the setting.
  Precious stones: One natural and untreated (!) Kashmir sapphire weighing 1.33 crt (see also certificat with the pictures). The finest stones came from India (Kashmir) since 1862 and have a rich blue colour that does not 'bleed' (i.e. change in different lights).
  Birthstones: Diamond is the birthstone (or month stone) for April and sapphire for September.
  Hallmarks: No trace.
  Weight: 3.00 gram (1.93 dwt)
  Ring size Continental: 58 & 18½ , Size US 8¼ , Size UK: Q
  Resizing: Free resizing (only for extreme resizing we have to charge).

      An engagement ring in Western tradition of no generally accepted form, worn by a woman indicating her engagement to be married. Conventionally, the ring is presented as a betrothal gift by a man to his prospective bride while he proposes marriage or directly after she accepts his marriage proposal. It represents a formal agreement to future marriage.

     In recent years such rings have normally been set with a gemstone, usually a diamond, as a solitaire, of varying sizes, cuts, styles, and cost, but in the 19th century some were set with a pearl. In the same century the custom arose in England of separate engagement ring and wedding ring, and in very recent years such rings have sometimes been made en suite as a matching pair of similar style. In recent years, antique gemstone engagement rings are rapidly gaining in popularity.

     In some countries, such as the United States and the United Kingdom, it is worn on the left-hand ring finger, while in other countries, such as Poland and Ukraine, it is customary for the ring to be worn on the right-hand. Similar traditions purportedly date to classical times, dating back from an early usage reportedly referring to the fourth finger of the left hand as containing the vena amoris or "vein of love". In the United States and Canada today it is becoming more common, but still quite rare, that a woman will also buy her partner an engagement ring (also called a pre-engagement ring, promise ring, or 'mangagement' ring) at the time of the engagement.

Old mine cut

      The style of cutting a diamond that is an early version of the brilliant cut. It was introduced in Brazil soon after diamonds were discovered there, and was originally known as the 'triple cut'. The girdle is cushion-shaped, and there was 32 facets on the crown plus an octagonal table, and 24 facets on the pavilion plus the culet. The 'Brazilian cut' has a similar crown but 8 additional small facets surrounding the culet.

      From: An Illustrated Dictionary of Jewelry, autor: Harold Newman, publishers: Thames and Hudson.