The answer is as follows: For men to wear gold is unlawful, regardless whether it is a ring, a watch, a cufflink, or even a tooth.
This is due to what is reported by Al-Bukhari and Muslim in their Sahihs from Al-Bara bin 'Azib, may Allaah be pleased with him, said, "The Messenger of Allaah (sallAllaahu `alayhi wa sallam) ordered us with seven and forbade us from seven, he forbade us from wearing gold rings, from drinking with silver (vessels)."
And because of what Ahmad, At-Tirmizi and An-Nasa'i recorded from the Hadeeth of Abu Musa Al-Ash'ari, that the Messenger of Allaah (sallAllaahu `alayhi wa sallam) said,
أحل الذهب والحرير لإناث أمتي وحرم على ذكورها
"Gold and silk are permitted for the women of my nation, prohibited for its men." (An-Nasa'i no. 5151, At-Tirmithi no. 1720 and Ahmad 4/394, 407)
As well as what is recorded in the Two Sahihs from the Hadeeth of Huthayfah, may Allaah be pleased with him, who said, "I heard Allaah's Messenger (sallAllaahu `alayhi wa sallam) saying:
لا تشربوا في آنية الذهب والفضة ولا تأكلوا في صحافها فإنها لهم في الدنيا ولنا في الآخرة
"Don't drink from vessels made from gold or silver and don't eat from their pots, for these are for them (disbelievers) in this world, and for us in the Hereafter." (Al-Bukhari no. 5426 and Muslim no. 2067)
And what is reported in Sahih Muslim from Umm Salamah, may Allaah be pleased with her, who said that Allaah's Messenger (sallAllaahu `alayhi wa sallam) said:
الذي يشرب في آنية الفضة إنما يجرجر في بطنه نار جهنم
"Whosoever drinks from a vessel made of silver, he has indeed dragged the fire of Hell into his stomach." (Al-Bukhari no. 5634 and Muslim no. 2065)
However, when it is absolutely necessary, one can use gold to replace a tooth, a nose, when there is nothing else to be used in place of it. As for rings, cuff-links, or watches, it is not allowed because of the absence of any need for that. This applies to men's watches and pens etc.
With Allaah is the facilitation to do what is right.
May Allaah peace and blessing on Muhammad (sallAllaahu `alayhi wa sallam), on his family, and on his Companions.