A swan hallmark with a "T" in the middle typically indicates that the item is made of silver and is part of the British hallmarking system. The swan represents the city of Birmingham, while the "T" denotes the year of assay, which helps identify when the item was tested for purity. This marking is an important factor for collectors and buyers to determine the authenticity and quality of silver items.
If it's a Birmingham hallmark (an Anchor) there is a complete list at http://www.theassayoffice.co.uk/date_letters.html
AT
t for tempo
The letter tav (ת), the last letter of the Hebrew alphabet, has a "t" sound.
Tender is the opposite of mean.
The word "atom" is not an acronym. The letter 't' in the word does not mean anything in particular.
t for tempo
If the letters TH are at the beginning of the 'Hallmark Stamp' it would be the initials of the manufacturer. If the T is separate at the end it could signify the year of manufacture (if English gold it would be 1968). Check on-line for Gold Hallmark Identification, but you will need to give all of the numbers, letters and symbols as they all have a meaning.
Trinidad and Tobago are sometimes abbreviated T T. In sports, TT can mean table tennis.
George T. Morgan is famous for designing and engraving the Morgan Silver Dollars (1878-1904 & 1921), which are named after him.
Trustworthy is a meaningful word. It begins with the letter t.