Praise be to Allaah.
Jareer ibn Abdullaah said: "I asked the Messenger of Allaah (Peace & Blessings of Allaah be upon Him) about an accidental glance at a woman. He commanded me to turn my gaze away." (Reported by al-Tirmidhi, who said: This is a saheeh hasan hadeeth. See al-Sunan, 2700).
Commenting on this hadeeth, al-Mubaarakpoori said: " Accidental means that his gaze fell on a non-mahram woman unintentionally. He commanded me to turn my gaze away means that he was not to look a second time, because the first glance was not by choice and would be forgiven, but any further glances would be counted as sin, and he should heed the words of Allaah (interpretation of the meaning): Tell the believing men to lower their gaze (from looking at forbidden things) [al-Noor 24:30]"
The Messenger of Allaah (Peace & Blessings of Allaah be upon Him) said: "O Ali, do not follow a glance with another, for you will be forgiven for the first, but not for the second." (Reported by al-Tirmidhi, 2701; see Saheeh al-Jaami, 7953)
In al-Tuhfah, he said: "The words do not follow a glance with another mean do not look again after the first glance. You will be forgiven for the first means that you will be forgiven if the first glance was unintentional, and but not for the second means that because the second glance was by choice, it will be counted against you."
So it is clear that deliberately looking at a non-mahram woman and continuing to look after a first accidental glance is haraam. It is forbidden to look at any part of her body, whether you think she is beautiful or not, whether it provokes sexual desire or not, whether it is accompanied by evil thoughts or not, and whether it leads to immoral deeds or not.
We ask Allaah to protect you and us from all haraam deeds. Allaah is the One Who guides to the Straight Path.