I know you said you "weren't getting into it" but I have to agree with all the posts about this not being ivory. Even without the yellowing etc the table is very mundane, cheap woods have been used with not just "unremarkable" grain but outright "too bloody busy" grain - it's cheap tat made for tourists and clearly not an antique of the era when ivory was still being used and the chances of real expensive ivory being used would be slim to zero.
Having just had a look at the cross sections of ivory for elephant and rhino it has a VERY distinct circular spiral pattern that would be clearly visible, even under whatever cheap applied finish this has on top.
It's definitely (according to multiple google images) not ivory of elephant, rhino or walrus. Nor from the looks of it is it any form of horn, antler etc. I don't even think it's bone, which is used as an ivory substitute more often than people might realise, but again, no visible markers such as yellowing or grain. I think the visible scratch marks are from sanding.
My suggestion would be for the owner to take the table to a verified dealer who has experience of ivory or bone and have him check, as they have equipment to do that, and on the extreme possibility it does turn out to be ivory, she can then either ask the dealer to sell it or whatever.
Unless the table has extreme sentimental value or you're doing this for free (which would be a mistake) the cost of doing this, even at a modest hourly rate would be enough to buy a replacement antique to go in it's place. This is several days work at the minimum to replicate what is there to a point it doesn't look bodged and thus make the already low value table, worthless.