Firstly, let's put to rest the idea that the wage gap is the result of discrimination on the individual level. The Korn Ferry Gender Pay Index analysed more than 12.3 million employees in 14,284 companies in 53 countries.

They found that men were paid on average 16.1 per cent more than women on a global level. But the gap fell to 5.3 per cent globally when evaluating the same job levels alone, such as people holding a director position. The gap was further narrowed to 1.5 per cent when considering the same level at the same company. If men and women at the same job level and in the same company were also in the same function, the gap shrank to 0.5 per cent.

"In Asia, the study found that women make, on average, 15 per cent less than their male counterparts. The average gap is widest - at 19.3 per cent - in Asia's mature markets, like Australia and New Zealand. But in Asia's growth markets like China and India, the gap is lower at 14.4 per cent; in the fast-growing markets like Indonesia and Vietnam, the gap narrows further to 11.5 per cent."

"Female employees are actually favoured in fast growing markets. Women in these markets are paid 1.3 percent more than men working at the same level at the same company. Women are paid 3.1 per cent more than men at the same level, company and function in these markets.""

https://www.businesstimes.com.sg/government-economy/fewer-women-in-good-paying-jobs-not-unequal-wages-behind-gender-pay-gap-korn

If you're arguing with a feminist and you present them these stats to counter the idea that the wage gap is caused by discrimination, they have a few choices. They can continue to cling to the idea that the residual 0.5% global gap favouring men is caused by wage discrimination - at which point, in order to maintain the facade of impartiality and logical consistency, they'd also have to admit that men are discriminated against and women are favoured in these fast-growing markets where they found a 3.1% gap favouring women - or, they'd have to admit that there are other additional factors that haven't been taken into account which can explain the 0.5% residual gap.

Their final choice is to contend that the discrimination does not happen on an individual basis, but that there is discrimination on the level of occupations and fields. Devaluation theory theorises that a higher value is attributed to jobs or occupations typically carried out by men or associated with male-stereotyped skills and so discrimination does not take place against individuals but against the types of jobs that they do. Based on these arguments, devaluation theory suggests that male-dominated occupations are more highly-rewarded than female-dominated occupations because ‘women’s work’ is devalued by social structures. 

However, there is basically no evidence for this assertion. This study tackles such claims. (Note, the link leads to a pdf that downloads)

https://osf.io/5u2nn/download

This study attempted to conduct the most rigorous test to date of the devaluation conjecture with regards to fields of study. They analysed data from the HIS Graduate Panel Study 1997 (N=4092), which allowed them to measure and control for characteristics that remained unobserved in earlier studies. What they found disconfirmed the idea that occupations which were dominated by women were being devalued because they were dominated by women. Instead, the reason why female-dominated occupations had lower wages was because women were more likely than men to self-select into disciplines that supplied cultural resources rather than fields which provided primarily economic resources. The latter, however, are known to be in higher labor market demand and thus to yield higher wages.

As the authors themselves say "Our results confirm Gerber and Cheung’s skepticism about adopting the causal interpretation to be found in earlier studies because our evidence leads to the probability that the relationship between sex composition and pay was entirely due to unobserved variable bias: earlier studies neglected the fact that fields vary in the degree to which they provide economic or cultural capital. We find that women disproportionately self-select into the latter, men into the former, and that this almost entirely explains the association between sex composition and wages. Based on this result, we extend Gerber and Cheung’s caution against hasty causal interpretations to evidence for devaluation from fixed-effects models because we doubt that the degree to which a discipline provides cultural or economic capital should be treated as time-constant."

"[T]he effect of sex composition on wages as derived from devaluation theory withers away entirely once we control for other field characteristics... Once we take into account that fields differ in more respects than just their sex composition, we find that sex composition itself is entirely unrelated to pay."

And if any feminist links you some study showing that the wage declines whenever a field turns from being male-dominated to female-dominated and asks "Well, why does that happen? It's the same field, but the wage still declined when women went into it" without also considering if the extent to which that occupation provides economic or cultural capital has changed overtime is, as the authors say, making a "hasty causal interpretation".

Women generally choose fields of study that furnish students with more cultural than economic capital and fewer quantitative skills. Fields that provide few economic capital and few quantitative skills should pay less for purely economic reasons. If a field changes from primarily providing economic capital to cultural capital, you'll see a drop in the wage, but also an increase in the amount of women who want to go into that field. That does not mean women's entry into a field or occupation causes a decline in wages any more than the finding that people in the UK tend to spend more in the shops when it's cold and less when it's hot means cold weather causes frenzied high-street spending. Drawing spurious conclusions about causality based solely off correlation is not a strong argument.