Kuznetsov
1889 — 1917
Green or blue stamp of the double-headed eagle over 'Т-ва М.С. Кузнецова' with the factory town below (Dulyovo, Riga, Tver…). The eagle appears after the partnership won the state warrant in 1889; town names localise production and price.
Imperial Porcelain (LFZ)
1936 — 2005
The interlaced ЛФЗ monogram (Lomonosov Porcelain Factory) in underglaze blue, red or green; export pieces add 'Made in USSR' or 'Lomonosov Russia'. Colour and wording narrow the date: blue underglaze for everyday wares, red overglaze often on gift lines, 'USSR' vanishing after 1991.
Meissen
1722 — present
Crossed swords in underglaze blue, taken from the Electoral Saxon arms. Sword form dates the piece: straight guards (18th c.), pommels (1763–74), star below (Marcolini, 1774–1814), dot between blades (1924–34). Strokes cut across the swords mark factory seconds.