Bernard,
tricky all that; and my English is not good enough to translate SG's thoughts: 'yes-no; on one hand-on the other hand' - sorry
According to SG, HEMAH marked glasses should be pre 1918 - age which, at the same time, he excludes for Steven's vase.
My two tazze are also not pre 1918 I'd say, and the price of '72 Kopeken' pressed into the glass could also lead to Belarussia at a certain time.
Here's a link to their website in many languages with interesting history data:
http://www.neman.by/en/index.php , view 'company profile'
Regarding the beautiful blue colour of yours: I do not dare to judge the age being pre or post WWII - Looking at my Saxonian and Bohemian pressed glass: why not pre 1939 before the war industry overtook?