How to narrow down portfolio entries shown under "all"?

I’d like to do something that’s a bit of a modification of the default behavior of the portfolio element included with the theme. We have many (44) entries included in our portfolio. We would like all relevant entries to be shown on a single page when different filters are selected. However, under the initial “All” filter, we would only like a selected 12 entries to appear on the home page, rather than the full 44. We’d prefer to show a selection of some of our best work, rather than overwhelming the user with all 44 entries at once.

Is there some way, through CSS or otherwise, this can be accomplished?

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