According to the Gemological Institute of America (GIA), VVS diamond clarity is better than SI diamond clarity. Very very slightly included diamonds are two tiers higher than SI diamonds. They have very very small inclusions that are barely noticeable, even under magnification.
A VVS diamond is not the highest clarity grade available. Next comes an internally flawless diamond and the rarest clarity grade of all, flawless diamonds.
An SI diamond isn't considered an eye clean diamond clarity grade. A diamond is considered eye-clean when it has no visible imperfections to the naked eye. SI1 diamonds are less likely to have as many or as obvious inclusions as SI2 diamonds.
In fact, there's only one clarity grade tier below slightly included diamonds: included diamonds, or I clarity diamonds. Clean Origin doesn't carry I clarity grade diamonds.
Though SI1 and si2 diamonds aren't considered eye-clean, that doesn't mean there aren't eye-clean SI1 and si2 diamonds available. They're just harder to find ones with fewer inclusions.
While a VVS diamond clarity grade may technically be "better" by clarity standards, it might not be better for your wallet if you're on a tight budget. Sometimes a less expensive SI clarity diamond ca be better than a VVS diamond. However, a larger diamond with a higher carat weight may require higher grades than SI clarity.
But if you're looking for a stone for your one-carat diamond ring, an SI clarity could be a good diamond for you, provided the other qualities are good as well.