I fancy myself to be a hard-core philatelist— at least when it comes to the stamps from South Africa in my collection.
To identify variants of a particular stamp that had been issued, I would say one needs at least a detailed stamp catalogue, a magnifying glass, and a stamp perforation gauge. Let’s also throw in an ultra-violet (UV) light, for stamps tagged with special inks.
The orange tree on this 6 penny stamp was a symbol for the Orange Free State province of the Union of South Africa.
(After 1994, the Orange Free State province name was shortened to Free State.)
*Then again, in the words of Henry Havelock Ellis ‘The absence of flaw is in itself a flaw’.
[Source: 2016 Stanley Gibbons Stamp Catalogue for Commonwealth & British Empire Stamps 1840-1970)