Rene Lalique 1920: Opalescent "Gui" Vase w/ Light Sepia Patina. Mint and Unusual

Description

René Lalique designed his "Gui" (mistletoe) vase in 1920, a fairly well known model which is not particularly rare, but I find this particular piece exceptional for two reasons: Firstly because it is both opalescent and has a light sepia patina, the combination is not frequent and works well, Secondly because it changes colors substantially under different light conditions. Photos 1 to 5 represent the vase as it appears at first, photos 6 to 9 as it looks when exposed to the light differently. It is the same vase and the pictures have not been photoshopped. This is known to happen with some Lalique vases made of Alexandrite glass, but Alexandrite is pink/purple and there is none here. So the phenomenon may be a result of the opalescence but I have never seen it to this extent.
The motif is one of mistletoe berries and leaves. The size is 17 cm tall (6 3/4").
"Gui" is photographed and described (photo 12) in Felix Marcilhac's large book (the unofficial Lalique "Bible"), on page 427 of the 2010 French printing under reference 948. The caption clarifies that it was made until the mid-1930's (it was removed from the 1937 catalogue) and never re-introduced later. The signature  is R LALIQUE  in raised block letters under the base and " Lalique France" etched manually (photos 10,11)).
The condition is excellent: No  chip, break or even visible scratch, and no missing to the patina. So the vase is exceptional on more than one account.