Found this in a letter I wrote to a friend years ago, thought it may be of use to some of you:

What is weight of the average silk tie? About 140-150 grams (at the most for maybe a high end tie)?

According to Ibn Hajar in al-Fath and al-Nawawi in al-Majmu’ one has to look at the weight, not the area covered, because silk can be spun and weaved to different sizes and thicknesses. So a patch of silk on the clothes is allowed, because it is not an article of clothing (“thawb”) but an accessory.

The Six except Bukhari narrate from Umar that he said:

The Messenger forbade us from wearing silk except of the place taken by two, three, or four fingers.

Ahmad narrates in his Musnad from Ibn Abbas that the Messenger of Allah forbade us from clothing made wholly from silk (al-thawb al-musammat min harir).

Ibn Abbas then says:

As for patches (al-‘alam) and lining (al-sudaa) then we see no problem in that.

(Ahmad, al-Musnad #1879) Al-Arnaut grades this narration in his marginalia on the Musnad saying: It is Sahih.

Ibn Abdul-Barr says in al-Istidhkar: Ibn Abbas’s statement is the tafsir for hadith in this issue and the majority of the scholars of the Salaf and Khalaf follow it.

Obviously if a person stays away from it out of pious caution (wara’) that is one thing, but the generalities of the texts do not seem to indicate that a person that wears a silk tie is necessarily doing something “haram”.