An attempt at a Númenorean tughra
Monogram of Elros Tar-Minyatur
An early monogram, displaying few of the features conventionally associated with later devices, or only in germ. The name of the king is in black (Tar-Minyatur) while 'Elenna' is written in red.
Monogram of Tar Vardamir, named Nólimon
This is certainly an invention of a scribe working long after the death of Vardamir, as the presence of features adopted much later attest - doubtless because the nominal second ruler of Númenor never reigned.
In this monogram, the star shape is more pronounced; the tehta representing the 'a' of 'Elenna' has also been moved to the centre of the device - representing, naturally, the summit of Meneltarma.
The conventional features are now all present: the star shape is evident, and only the tehtar representing the 'a' in 'Tar' and 'Elenna' have been retained, in symbolic positions, one representing Meneltarma and the other the promontory of Forrostar or, in some interpretations, the stars (clearly the choice made by the scribe who invented the device of Vardamir, perhaps in reverence towards the Valië for whom the king was named).
Monogram of Anardil, Tar Aldarion
In this monogram the tehtar are now circumflexes. The king's two names are present, one on land, the other at sea. A ship has been added.
The names of both of the Ruling Queen's parents have been included in this monogram, one that is particularly ornate for the period.
explanation: ever since visiting Istanbul a year ago I've been interested in the tughra, a calligraphic monogram used by Ottoman sultans, much as seals were elsewhere (to authentify the sultan's correspondence or official documents), and also on a variety of objects, e.g. here on a wall at Topkapı palace or here on a coin). They started out fairly simple but some ended up being very ornate and gorgeous; and they typically contained the name of the sultan, that of his father, as well as things like epithets and prayers, and also had some conventional features which made them easy to recognise - the beyze (egg), i.e. the loops on the left hand side, and the three tuğ (flagstaff) at the top.
Anyway I've been trying to come up with a Númenorean version and ended up with this, combining some form of the prefix 'Tar' and the name 'Elenna'. As it happens the Ottoman tughra may have had a cartographic element as well - the loops on the left are said to possibly symbolise the two seas - Black Sea, Mediterranean - on whose shores they ruled. Hence the star shape (which I wanted from the start really) and Meneltarma.
I hope I haven't made too many mistakes with the tengwar. I used the classical mode which I've since gathered may not have been the one in use in Númenor or at least not late in Númenor's history... in any case I've taken some wild liberties with the layout anyway, sorry Jirt.